From 5387e206b1aea05074881a233bdc874b098d4e3b Mon Sep 17 00:00:00 2001
From: sfilippone <filippone.salvatore@gmail.com>
Date: Fri, 24 Nov 2023 16:07:22 +0100
Subject: [PATCH] Fixed sample programs

---
 Makefile                                      |   4 +-
 samples/advanced/pdegen/Makefile              |  28 ++---
 samples/advanced/pdegen/amg_d_pde2d.F90       |  44 ++++----
 .../advanced/pdegen/amg_d_pde2d_base_mod.f90  |  56 +++++-----
 .../advanced/pdegen/amg_d_pde2d_box_mod.f90   |   4 +-
 .../advanced/pdegen/amg_d_pde2d_exp_mod.f90   |   4 +-
 .../advanced/pdegen/amg_d_pde2d_gauss_mod.f90 |  89 +++++++++++++++
 samples/advanced/pdegen/amg_d_pde3d.F90       |  44 ++++----
 .../advanced/pdegen/amg_d_pde3d_base_mod.f90  |  72 ++++++-------
 .../advanced/pdegen/amg_d_pde3d_box_mod.f90   | 101 ++++++++++++++++++
 .../advanced/pdegen/amg_d_pde3d_exp_mod.f90   |   4 +-
 .../advanced/pdegen/amg_d_pde3d_gauss_mod.f90 |   4 +-
 samples/advanced/pdegen/amg_s_pde2d.F90       |  44 ++++----
 .../advanced/pdegen/amg_s_pde2d_base_mod.f90  |  56 +++++-----
 .../advanced/pdegen/amg_s_pde2d_box_mod.f90   |   4 +-
 .../advanced/pdegen/amg_s_pde2d_exp_mod.f90   |   4 +-
 .../advanced/pdegen/amg_s_pde2d_gauss_mod.f90 |  89 +++++++++++++++
 samples/advanced/pdegen/amg_s_pde3d.F90       |  44 ++++----
 .../advanced/pdegen/amg_s_pde3d_base_mod.f90  |  72 ++++++-------
 .../advanced/pdegen/amg_s_pde3d_box_mod.f90   | 101 ++++++++++++++++++
 .../advanced/pdegen/amg_s_pde3d_exp_mod.f90   |   4 +-
 .../advanced/pdegen/amg_s_pde3d_gauss_mod.f90 |   4 +-
 22 files changed, 638 insertions(+), 238 deletions(-)
 create mode 100644 samples/advanced/pdegen/amg_d_pde2d_gauss_mod.f90
 create mode 100644 samples/advanced/pdegen/amg_d_pde3d_box_mod.f90
 create mode 100644 samples/advanced/pdegen/amg_s_pde2d_gauss_mod.f90
 create mode 100644 samples/advanced/pdegen/amg_s_pde3d_box_mod.f90

diff --git a/Makefile b/Makefile
index fb87ee99..ecd50936 100644
--- a/Makefile
+++ b/Makefile
@@ -3,9 +3,9 @@ include Make.inc
 
 all:  objs lib
 
-objs: amgp cbnd
+objs: libdir amgp cbnd
 
-lib: libdir objs
+lib:  objs
 	cd amgprec && $(MAKE) lib
 	cd cbind && $(MAKE)  lib
 
diff --git a/samples/advanced/pdegen/Makefile b/samples/advanced/pdegen/Makefile
index b5092a22..fc9a7f21 100644
--- a/samples/advanced/pdegen/Makefile
+++ b/samples/advanced/pdegen/Makefile
@@ -8,23 +8,27 @@ FINCLUDES=$(FMFLAG). $(FMFLAG)$(AMGMODDIR) $(FMFLAG)$(AMGINCDIR) $(PSBLAS_INCLUD
 
 LINKOPT=
 EXEDIR=./runs
+DGEN2D=amg_d_pde2d_base_mod.o amg_d_pde2d_exp_mod.o amg_d_pde2d_gauss_mod.o amg_d_pde2d_box_mod.o
+DGEN3D=amg_d_pde3d_base_mod.o amg_d_pde3d_exp_mod.o amg_d_pde3d_gauss_mod.o amg_d_pde3d_box_mod.o 	
+SGEN2D=amg_s_pde2d_base_mod.o amg_s_pde2d_exp_mod.o amg_s_pde2d_gauss_mod.o amg_s_pde2d_box_mod.o
+SGEN3D=amg_s_pde3d_base_mod.o amg_s_pde3d_exp_mod.o amg_s_pde3d_gauss_mod.o amg_s_pde3d_box_mod.o 	
 
 all: amg_s_pde3d amg_d_pde3d amg_s_pde2d amg_d_pde2d
 
-amg_d_pde3d: amg_d_pde3d.o amg_d_genpde_mod.o amg_d_pde3d_base_mod.o amg_d_pde3d_exp_mod.o amg_d_pde3d_gauss_mod.o data_input.o
-	$(FLINK) $(LINKOPT) amg_d_pde3d.o  amg_d_genpde_mod.o amg_d_pde3d_base_mod.o amg_d_pde3d_exp_mod.o amg_d_pde3d_gauss_mod.o data_input.o -o amg_d_pde3d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
+amg_d_pde3d: amg_d_pde3d.o amg_d_genpde_mod.o $(DGEN3D) data_input.o
+	$(FLINK) $(LINKOPT) amg_d_pde3d.o  amg_d_genpde_mod.o $(DGEN3D) data_input.o -o amg_d_pde3d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
 	/bin/mv amg_d_pde3d $(EXEDIR)
 
-amg_s_pde3d: amg_s_pde3d.o amg_s_genpde_mod.o amg_s_pde3d_base_mod.o  amg_s_pde3d_exp_mod.o amg_s_pde3d_gauss_mod.o data_input.o
-	$(FLINK) $(LINKOPT) amg_s_pde3d.o  amg_s_genpde_mod.o amg_s_pde3d_base_mod.o amg_s_pde3d_exp_mod.o amg_s_pde3d_gauss_mod.o data_input.o -o amg_s_pde3d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
+amg_s_pde3d: amg_s_pde3d.o amg_s_genpde_mod.o $(SGEN3D) data_input.o
+	$(FLINK) $(LINKOPT) amg_s_pde3d.o  amg_s_genpde_mod.o  $(SGEN3D) data_input.o -o amg_s_pde3d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
 	/bin/mv amg_s_pde3d $(EXEDIR)
 
-amg_d_pde2d: amg_d_pde2d.o amg_d_genpde_mod.o amg_d_pde2d_base_mod.o amg_d_pde2d_exp_mod.o amg_d_pde2d_box_mod.o data_input.o
-	$(FLINK) $(LINKOPT) amg_d_pde2d.o amg_d_genpde_mod.o amg_d_pde2d_base_mod.o amg_d_pde2d_exp_mod.o amg_d_pde2d_box_mod.o data_input.o -o amg_d_pde2d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
+amg_d_pde2d: amg_d_pde2d.o amg_d_genpde_mod.o  $(DGEN2D) data_input.o
+	$(FLINK) $(LINKOPT) amg_d_pde2d.o amg_d_genpde_mod.o $(DGEN2D) data_input.o -o amg_d_pde2d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
 	/bin/mv amg_d_pde2d $(EXEDIR)
 
-amg_s_pde2d: amg_s_pde2d.o amg_s_genpde_mod.o amg_s_pde2d_base_mod.o amg_s_pde2d_exp_mod.o amg_s_pde2d_box_mod.o data_input.o
-	$(FLINK) $(LINKOPT) amg_s_pde2d.o amg_s_genpde_mod.o amg_s_pde2d_base_mod.o amg_s_pde2d_exp_mod.o amg_s_pde2d_box_mod.o data_input.o -o amg_s_pde2d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
+amg_s_pde2d: amg_s_pde2d.o amg_s_genpde_mod.o $(SGEN2D) data_input.o
+	$(FLINK) $(LINKOPT) amg_s_pde2d.o amg_s_genpde_mod.o $(SGEN2D) data_input.o -o amg_s_pde2d $(AMG_LIBS) $(PSBLAS_LIBS) $(LDLIBS)
 	/bin/mv amg_s_pde2d $(EXEDIR)
 
 amg_d_pde3d_rebld: amg_d_pde3d_rebld.o  data_input.o
@@ -33,10 +37,10 @@ amg_d_pde3d_rebld: amg_d_pde3d_rebld.o  data_input.o
 
 amg_d_pde3d.o amg_s_pde3d.o amg_d_pde2d.o amg_s_pde2d.o: data_input.o
 
-amg_d_pde3d.o: amg_d_genpde_mod.o amg_d_pde3d_base_mod.o amg_d_pde3d_exp_mod.o amg_d_pde3d_gauss_mod.o
-amg_s_pde3d.o: amg_s_genpde_mod.o amg_s_pde3d_base_mod.o amg_s_pde3d_exp_mod.o amg_s_pde3d_gauss_mod.o
-amg_d_pde2d.o: amg_d_genpde_mod.o amg_d_pde2d_base_mod.o amg_d_pde2d_exp_mod.o amg_d_pde2d_box_mod.o
-amg_s_pde2d.o: amg_s_genpde_mod.o amg_s_pde2d_base_mod.o amg_s_pde2d_exp_mod.o amg_s_pde2d_box_mod.o
+amg_d_pde3d.o: amg_d_genpde_mod.o $(DGEN3D)
+amg_s_pde3d.o: amg_s_genpde_mod.o $(SGEN3D) 
+amg_d_pde2d.o: amg_d_genpde_mod.o $(DGEN2D)
+amg_s_pde2d.o: amg_s_genpde_mod.o $(SGEN2D)
 
 check: all
 	cd runs && ./amg_d_pde2d <amg_pde2d.inp && ./amg_s_pde2d<amg_pde2d.inp
diff --git a/samples/advanced/pdegen/amg_d_pde2d.F90 b/samples/advanced/pdegen/amg_d_pde2d.F90
index 6ffb519b..8f1a3411 100644
--- a/samples/advanced/pdegen/amg_d_pde2d.F90
+++ b/samples/advanced/pdegen/amg_d_pde2d.F90
@@ -72,6 +72,7 @@ program amg_d_pde2d
   use amg_d_pde2d_base_mod
   use amg_d_pde2d_exp_mod
   use amg_d_pde2d_box_mod
+  use amg_d_pde2d_gauss_mod
   use amg_d_genpde_mod
 #if defined(OPENMP)
   use omp_lib
@@ -124,16 +125,16 @@ program amg_d_pde2d
     integer(psb_ipk_)  :: outer_sweeps ! number of outer sweeps: sweeps for 1-level,
     ! AMG cycles for ML
     ! general AMG data
-    character(len=16)  :: mlcycle      ! AMG cycle type
+    character(len=32)  :: mlcycle      ! AMG cycle type
     integer(psb_ipk_)  :: maxlevs     ! maximum number of levels in AMG preconditioner
 
     ! AMG aggregation
-    character(len=16)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
-    character(len=16)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
-    character(len=16)  :: aggr_type   ! Type of aggregation SOC1, SOC2, MATCHBOXP
+    character(len=32)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
+    character(len=32)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
+    character(len=32)  :: aggr_type   ! Type of aggregation SOC1, SOC2, MATCHBOXP
     integer(psb_ipk_)  :: aggr_size   ! Requested size of the aggregates for MATCHBOXP
-    character(len=16)  :: aggr_ord    ! ordering for aggregation: NATURAL, DEGREE
-    character(len=16)  :: aggr_filter ! filtering: FILTER, NO_FILTER
+    character(len=32)  :: aggr_ord    ! ordering for aggregation: NATURAL, DEGREE
+    character(len=32)  :: aggr_filter ! filtering: FILTER, NO_FILTER
     real(psb_dpk_)     :: mncrratio  ! minimum aggregation ratio
     real(psb_dpk_), allocatable :: athresv(:) ! smoothed aggregation threshold vector
     integer(psb_ipk_)  :: thrvsz      ! size of threshold vector
@@ -141,39 +142,39 @@ program amg_d_pde2d
     integer(psb_ipk_)  :: csizepp     ! minimum size of coarsest matrix per process
 
     ! AMG smoother or pre-smoother; also 1-lev preconditioner
-    character(len=16)  :: smther       ! (pre-)smoother type: BJAC, AS
+    character(len=32)  :: smther       ! (pre-)smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps      ! (pre-)smoother / 1-lev prec. sweeps
     integer(psb_ipk_)  :: novr         ! number of overlap layers
-    character(len=16)  :: restr        ! restriction over application of AS
-    character(len=16)  :: prol         ! prolongation over application of AS
-    character(len=16)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr        ! restriction over application of AS
+    character(len=32)  :: prol         ! prolongation over application of AS
+    character(len=32)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps      ! inner solver sweeps
-    character(len=16)  :: variant      ! AINV variant: LLK, etc
+    character(len=32)  :: variant      ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill         ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill      ! Inverse fill-in for INVK
     real(psb_dpk_)      :: thr          ! threshold for ILUT factorization
 
     ! AMG post-smoother; ignored by 1-lev preconditioner
-    character(len=16)  :: smther2      ! post-smoother type: BJAC, AS
+    character(len=32)  :: smther2      ! post-smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps2     ! post-smoother sweeps
     integer(psb_ipk_)  :: novr2        ! number of overlap layers
-    character(len=16)  :: restr2       ! restriction  over application of AS
-    character(len=16)  :: prol2        ! prolongation over application of AS
-    character(len=16)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr2       ! restriction  over application of AS
+    character(len=32)  :: prol2        ! prolongation over application of AS
+    character(len=32)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps2     ! inner solver sweeps
-    character(len=16)  :: variant2     ! AINV variant: LLK, etc
+    character(len=32)  :: variant2     ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill2        ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill2     ! Inverse fill-in for INVK
     real(psb_dpk_)      :: thr2         ! threshold for ILUT factorization
 
     ! coarsest-level solver
-    character(len=16)  :: cmat        ! coarsest matrix layout: REPL, DIST
-    character(len=16)  :: csolve      ! coarsest-lev solver: BJAC, SLUDIST (distr.
+    character(len=32)  :: cmat        ! coarsest matrix layout: REPL, DIST
+    character(len=32)  :: csolve      ! coarsest-lev solver: BJAC, SLUDIST (distr.
                                       ! mat.); UMF, MUMPS, SLU, ILU, ILUT, MILU
                                       ! (repl. mat.)
-    character(len=16)  :: csbsolve    ! coarsest-lev local subsolver: ILU, ILUT,
+    character(len=32)  :: csbsolve    ! coarsest-lev local subsolver: ILU, ILUT,
                                       ! MILU, UMF, MUMPS, SLU
     integer(psb_ipk_)  :: cfill       ! fill-in for incomplete LU factorization
     real(psb_dpk_)     :: cthres      ! threshold for ILUT factorization
@@ -241,13 +242,16 @@ program amg_d_pde2d
   select case(psb_toupper(trim(pdecoeff)))
   case("CONST")
     call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
-        & a1,a2,b1,b2,c,g,info)
+        & a1_base,a2_base,b1_base,b2_base,c_base,g_base,info)
   case("EXP")
     call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_exp,a2_exp,b1_exp,b2_exp,c_exp,g_exp,info)
   case("BOX")
     call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_box,a2_box,b1_box,b2_box,c_box,g_box,info)
+  case("GAUSS")
+    call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
+        & a1_gauss,a2_gauss,b1_gauss,b2_gauss,c_gauss,g_gauss,info)
   case default
     info=psb_err_from_subroutine_
     ch_err='amg_gen_pdecoeff'
diff --git a/samples/advanced/pdegen/amg_d_pde2d_base_mod.f90 b/samples/advanced/pdegen/amg_d_pde2d_base_mod.f90
index a406e90e..e6613370 100644
--- a/samples/advanced/pdegen/amg_d_pde2d_base_mod.f90
+++ b/samples/advanced/pdegen/amg_d_pde2d_base_mod.f90
@@ -38,52 +38,52 @@ module amg_d_pde2d_base_mod
   use psb_base_mod, only : psb_dpk_, dzero, done
   real(psb_dpk_), save, private :: epsilon=done/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm2d_base(dat)
     real(psb_dpk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm2d_base
   !
   ! functions parametrizing the differential equation
   !
-  function b1(x,y)
+  function b1_base(x,y)
     implicit none 
-    real(psb_dpk_) :: b1
+    real(psb_dpk_) :: b1_base
     real(psb_dpk_), intent(in) :: x,y
-    b1 = dzero/1.414_psb_dpk_
-  end function b1
-  function b2(x,y)
+    b1_base = dzero/1.414_psb_dpk_
+  end function b1_base
+  function b2_base(x,y)
     implicit none 
-    real(psb_dpk_) ::  b2
+    real(psb_dpk_) ::  b2_base
     real(psb_dpk_), intent(in) :: x,y
-    b2 = dzero/1.414_psb_dpk_
-  end function b2
-  function c(x,y)
+    b2_base = dzero/1.414_psb_dpk_
+  end function b2_base
+  function c_base(x,y)
     implicit none 
-    real(psb_dpk_) ::  c
+    real(psb_dpk_) ::  c_base
     real(psb_dpk_), intent(in) :: x,y
-    c = dzero
-  end function c
-  function a1(x,y)
+    c_base = dzero
+  end function c_base
+  function a1_base(x,y)
     implicit none 
-    real(psb_dpk_) ::  a1
+    real(psb_dpk_) ::  a1_base
     real(psb_dpk_), intent(in) :: x,y
-    a1=done*epsilon
-  end function a1
-  function a2(x,y)
+    a1_base=done*epsilon
+  end function a1_base
+  function a2_base(x,y)
     implicit none 
-    real(psb_dpk_) ::  a2
+    real(psb_dpk_) ::  a2_base
     real(psb_dpk_), intent(in) :: x,y
-    a2=done*epsilon
-  end function a2
-  function g(x,y)
+    a2_base=done*epsilon
+  end function a2_base
+  function g_base(x,y)
     implicit none 
-    real(psb_dpk_) ::  g
+    real(psb_dpk_) ::  g_base
     real(psb_dpk_), intent(in) :: x,y
-    g = dzero
+    g_base = dzero
     if (x == done) then
-      g = done
+      g_base = done
     else if (x == dzero) then
-      g = done
+      g_base = done
     end if
-  end function g
+  end function g_base
 end module amg_d_pde2d_base_mod
diff --git a/samples/advanced/pdegen/amg_d_pde2d_box_mod.f90 b/samples/advanced/pdegen/amg_d_pde2d_box_mod.f90
index db743633..11d5770b 100644
--- a/samples/advanced/pdegen/amg_d_pde2d_box_mod.f90
+++ b/samples/advanced/pdegen/amg_d_pde2d_box_mod.f90
@@ -38,10 +38,10 @@ module amg_d_pde2d_box_mod
   use psb_base_mod, only : psb_dpk_, dzero, done
   real(psb_dpk_), save, private :: epsilon=done/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm2d_box(dat)
     real(psb_dpk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm2d_box
   !
   ! functions parametrizing the differential equation
   !
diff --git a/samples/advanced/pdegen/amg_d_pde2d_exp_mod.f90 b/samples/advanced/pdegen/amg_d_pde2d_exp_mod.f90
index 5dab37bc..76a733fc 100644
--- a/samples/advanced/pdegen/amg_d_pde2d_exp_mod.f90
+++ b/samples/advanced/pdegen/amg_d_pde2d_exp_mod.f90
@@ -38,10 +38,10 @@ module amg_d_pde2d_exp_mod
   use psb_base_mod, only : psb_dpk_, done, dzero
   real(psb_dpk_), save, private :: epsilon=done/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm2d_exp(dat)
     real(psb_dpk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm2d_exp
   !
   ! functions parametrizing the differential equation
   !
diff --git a/samples/advanced/pdegen/amg_d_pde2d_gauss_mod.f90 b/samples/advanced/pdegen/amg_d_pde2d_gauss_mod.f90
new file mode 100644
index 00000000..93b911ea
--- /dev/null
+++ b/samples/advanced/pdegen/amg_d_pde2d_gauss_mod.f90
@@ -0,0 +1,89 @@
+!
+!
+!                             AMG4PSBLAS version 1.0
+!    Algebraic Multigrid Package
+!               based on PSBLAS (Parallel Sparse BLAS version 3.7)
+!
+!    (C) Copyright 2021
+!
+!        Salvatore Filippone
+!        Pasqua D'Ambra
+!        Fabio Durastante
+!
+!    Redistribution and use in source and binary forms, with or without
+!    modification, are permitted provided that the following conditions
+!    are met:
+!      1. Redistributions of source code must retain the above copyright
+!         notice, this list of conditions and the following disclaimer.
+!      2. Redistributions in binary form must reproduce the above copyright
+!         notice, this list of conditions, and the following disclaimer in the
+!         documentation and/or other materials provided with the distribution.
+!      3. The name of the AMG4PSBLAS group or the names of its contributors may
+!         not be used to endorse or promote products derived from this
+!         software without specific written permission.
+!
+!    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+!    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+!    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+!    PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AMG4PSBLAS GROUP OR ITS CONTRIBUTORS
+!    BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+!    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+!    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+!    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+!    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+!    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+!    POSSIBILITY OF SUCH DAMAGE.
+!
+module amg_d_pde2d_gauss_mod
+  use psb_base_mod, only : psb_dpk_, done, dzero
+  real(psb_dpk_), save, private :: epsilon=done/80
+contains
+  subroutine pde_set_parm2d_gauss(dat)
+    real(psb_dpk_), intent(in) :: dat
+    epsilon = dat
+  end subroutine pde_set_parm2d_gauss
+  !
+  ! functions parametrizing the differential equation
+  !
+  function b1_gauss(x,y)
+    implicit none 
+    real(psb_dpk_) :: b1_gauss
+    real(psb_dpk_), intent(in) :: x,y
+    b1_gauss=done/sqrt(3.0_psb_dpk_)-2*x*exp(-(x**2+y**2))
+  end function b1_gauss
+  function b2_gauss(x,y)
+    implicit none 
+    real(psb_dpk_) ::  b2_gauss
+    real(psb_dpk_), intent(in) :: x,y
+    b2_gauss=done/sqrt(3.0_psb_dpk_)-2*y*exp(-(x**2+y**2))
+  end function b2_gauss
+  function c_gauss(x,y)
+    implicit none 
+    real(psb_dpk_) ::  c_gauss
+    real(psb_dpk_), intent(in) :: x,y
+    c_gauss=dzero
+  end function c_gauss
+  function a1_gauss(x,y)
+    implicit none 
+    real(psb_dpk_) ::  a1_gauss
+    real(psb_dpk_), intent(in) :: x,y
+    a1_gauss=epsilon*exp(-(x**2+y**2))
+  end function a1_gauss
+  function a2_gauss(x,y)
+    implicit none 
+    real(psb_dpk_) ::  a2_gauss
+    real(psb_dpk_), intent(in) :: x,y
+    a2_gauss=epsilon*exp(-(x**2+y**2))
+  end function a2_gauss
+  function g_gauss(x,y)
+    implicit none 
+    real(psb_dpk_) ::  g_gauss
+    real(psb_dpk_), intent(in) :: x,y
+    g_gauss = dzero
+    if (x == done) then
+      g_gauss = done
+    else if (x == dzero) then
+      g_gauss = done
+    end if
+  end function g_gauss
+end module amg_d_pde2d_gauss_mod
diff --git a/samples/advanced/pdegen/amg_d_pde3d.F90 b/samples/advanced/pdegen/amg_d_pde3d.F90
index 006c6d6f..031179fe 100644
--- a/samples/advanced/pdegen/amg_d_pde3d.F90
+++ b/samples/advanced/pdegen/amg_d_pde3d.F90
@@ -72,6 +72,7 @@ program amg_d_pde3d
   use data_input
   use amg_d_pde3d_base_mod
   use amg_d_pde3d_exp_mod
+  use amg_d_pde3d_box_mod
   use amg_d_pde3d_gauss_mod
   use amg_d_genpde_mod
 #if defined(OPENMP)
@@ -125,16 +126,16 @@ program amg_d_pde3d
     integer(psb_ipk_)  :: outer_sweeps ! number of outer sweeps: sweeps for 1-level,
     ! AMG cycles for ML
     ! general AMG data
-    character(len=16)  :: mlcycle      ! AMG cycle type
+    character(len=32)  :: mlcycle      ! AMG cycle type
     integer(psb_ipk_)  :: maxlevs      ! maximum number of levels in AMG preconditioner
 
     ! AMG aggregation
-    character(len=16)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
-    character(len=16)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
-    character(len=16)  :: aggr_type    ! Type of aggregation SOC1, SOC2, MATCHBOXP
+    character(len=32)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
+    character(len=32)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
+    character(len=32)  :: aggr_type    ! Type of aggregation SOC1, SOC2, MATCHBOXP
     integer(psb_ipk_)  :: aggr_size    ! Requested size of the aggregates for MATCHBOXP
-    character(len=16)  :: aggr_ord     ! ordering for aggregation: NATURAL, DEGREE
-    character(len=16)  :: aggr_filter  ! filtering: FILTER, NO_FILTER
+    character(len=32)  :: aggr_ord     ! ordering for aggregation: NATURAL, DEGREE
+    character(len=32)  :: aggr_filter  ! filtering: FILTER, NO_FILTER
     real(psb_dpk_)      :: mncrratio    ! minimum aggregation ratio
     real(psb_dpk_), allocatable :: athresv(:) ! smoothed aggregation threshold vector
     integer(psb_ipk_)  :: thrvsz       ! size of threshold vector
@@ -142,39 +143,39 @@ program amg_d_pde3d
     integer(psb_ipk_)  :: csizepp      ! minimum size of coarsest matrix per process
 
     ! AMG smoother or pre-smoother; also 1-lev preconditioner
-    character(len=16)  :: smther       ! (pre-)smoother type: BJAC, AS
+    character(len=32)  :: smther       ! (pre-)smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps      ! (pre-)smoother / 1-lev prec. sweeps
     integer(psb_ipk_)  :: novr         ! number of overlap layers
-    character(len=16)  :: restr        ! restriction over application of AS
-    character(len=16)  :: prol         ! prolongation over application of AS
-    character(len=16)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr        ! restriction over application of AS
+    character(len=32)  :: prol         ! prolongation over application of AS
+    character(len=32)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps      ! inner solver sweeps
-    character(len=16)  :: variant      ! AINV variant: LLK, etc
+    character(len=32)  :: variant      ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill         ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill      ! Inverse fill-in for INVK
     real(psb_dpk_)      :: thr          ! threshold for ILUT factorization
 
     ! AMG post-smoother; ignored by 1-lev preconditioner
-    character(len=16)  :: smther2      ! post-smoother type: BJAC, AS
+    character(len=32)  :: smther2      ! post-smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps2     ! post-smoother sweeps
     integer(psb_ipk_)  :: novr2        ! number of overlap layers
-    character(len=16)  :: restr2       ! restriction  over application of AS
-    character(len=16)  :: prol2        ! prolongation over application of AS
-    character(len=16)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr2       ! restriction  over application of AS
+    character(len=32)  :: prol2        ! prolongation over application of AS
+    character(len=32)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps2     ! inner solver sweeps
-    character(len=16)  :: variant2     ! AINV variant: LLK, etc
+    character(len=32)  :: variant2     ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill2        ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill2     ! Inverse fill-in for INVK
     real(psb_dpk_)      :: thr2         ! threshold for ILUT factorization
 
     ! coarsest-level solver
-    character(len=16)  :: cmat         ! coarsest matrix layout: REPL, DIST
-    character(len=16)  :: csolve       ! coarsest-lev solver: BJAC, SLUDIST (distr.
+    character(len=32)  :: cmat         ! coarsest matrix layout: REPL, DIST
+    character(len=32)  :: csolve       ! coarsest-lev solver: BJAC, SLUDIST (distr.
                                        ! mat.); UMF, MUMPS, SLU, ILU, ILUT, MILU
                                        ! (repl. mat.)
-    character(len=16)  :: csbsolve     ! coarsest-lev local subsolver: ILU, ILUT,
+    character(len=32)  :: csbsolve     ! coarsest-lev local subsolver: ILU, ILUT,
                                        ! MILU, UMF, MUMPS, SLU
     integer(psb_ipk_)  :: cfill        ! fill-in for incomplete LU factorization
     real(psb_dpk_)     :: cthres        ! threshold for ILUT factorization
@@ -243,10 +244,13 @@ program amg_d_pde3d
   select case(psb_toupper(trim(pdecoeff)))
   case("CONST")
     call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
-        & a1,a2,a3,b1,b2,b3,c,g,info)
+        & a1_base,a2_base,a3_base,b1_base,b2_base,b3_base,c_base,g_base,info)
   case("EXP")
     call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_exp,a2_exp,a3_exp,b1_exp,b2_exp,b3_exp,c_exp,g_exp,info)
+  case("BOX")
+    call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
+        & a1_box,a2_box,a3_box,b1_box,b2_box,b3_box,c_box,g_box,info)
   case("GAUSS")
     call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_gauss,a2_gauss,a3_gauss,b1_gauss,b2_gauss,b3_gauss,c_gauss,g_gauss,info)
diff --git a/samples/advanced/pdegen/amg_d_pde3d_base_mod.f90 b/samples/advanced/pdegen/amg_d_pde3d_base_mod.f90
index 57a43511..4e954654 100644
--- a/samples/advanced/pdegen/amg_d_pde3d_base_mod.f90
+++ b/samples/advanced/pdegen/amg_d_pde3d_base_mod.f90
@@ -38,64 +38,64 @@ module amg_d_pde3d_base_mod
   use psb_base_mod, only : psb_dpk_, done, dzero
   real(psb_dpk_), save, private :: epsilon=done/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm3d_base(dat)
     real(psb_dpk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm3d_base
   !
   ! functions parametrizing the differential equation
   !
-  function b1(x,y,z)
+  function b1_base(x,y,z)
     implicit none 
-    real(psb_dpk_) :: b1
+    real(psb_dpk_) :: b1_base
     real(psb_dpk_), intent(in) :: x,y,z
-    b1=done/sqrt(3.0_psb_dpk_)
-  end function b1
-  function b2(x,y,z)
+    b1_base=dzero/sqrt(3.0_psb_dpk_)
+  end function b1_base
+  function b2_base(x,y,z)
     implicit none 
-    real(psb_dpk_) ::  b2
+    real(psb_dpk_) ::  b2_base
     real(psb_dpk_), intent(in) :: x,y,z
-    b2=done/sqrt(3.0_psb_dpk_)
-  end function b2
-  function b3(x,y,z)
+    b2_base=dzero/sqrt(3.0_psb_dpk_)
+  end function b2_base
+  function b3_base(x,y,z)
     implicit none 
-    real(psb_dpk_) ::  b3
+    real(psb_dpk_) ::  b3_base
     real(psb_dpk_), intent(in) :: x,y,z
-    b3=done/sqrt(3.0_psb_dpk_)
-  end function b3
-  function c(x,y,z)
+    b3_base=dzero/sqrt(3.0_psb_dpk_)
+  end function b3_base
+  function c_base(x,y,z)
     implicit none 
-    real(psb_dpk_) ::  c
+    real(psb_dpk_) ::  c_base
     real(psb_dpk_), intent(in) :: x,y,z
-    c=dzero
-  end function c
-  function a1(x,y,z)
+    c_base=dzero
+  end function c_base
+  function a1_base(x,y,z)
     implicit none 
-    real(psb_dpk_) ::  a1
+    real(psb_dpk_) ::  a1_base
     real(psb_dpk_), intent(in) :: x,y,z
-    a1=epsilon
-  end function a1
-  function a2(x,y,z)
+    a1_base=epsilon
+  end function a1_base
+  function a2_base(x,y,z)
     implicit none 
-    real(psb_dpk_) ::  a2
+    real(psb_dpk_) ::  a2_base
     real(psb_dpk_), intent(in) :: x,y,z
-    a2=epsilon
-  end function a2
-  function a3(x,y,z)
+    a2_base=epsilon
+  end function a2_base
+  function a3_base(x,y,z)
     implicit none 
-    real(psb_dpk_) ::  a3
+    real(psb_dpk_) ::  a3_base
     real(psb_dpk_), intent(in) :: x,y,z
-    a3=epsilon
-  end function a3
-  function g(x,y,z)
+    a3_base=epsilon
+  end function a3_base
+  function g_base(x,y,z)
     implicit none 
-    real(psb_dpk_) ::  g
+    real(psb_dpk_) ::  g_base
     real(psb_dpk_), intent(in) :: x,y,z
-    g = dzero
+    g_base = dzero
     if (x == done) then
-      g = done
+      g_base = done
     else if (x == dzero) then
-      g = done
+      g_base = done
     end if
-  end function g
+  end function g_base
 end module amg_d_pde3d_base_mod
diff --git a/samples/advanced/pdegen/amg_d_pde3d_box_mod.f90 b/samples/advanced/pdegen/amg_d_pde3d_box_mod.f90
new file mode 100644
index 00000000..7062ad27
--- /dev/null
+++ b/samples/advanced/pdegen/amg_d_pde3d_box_mod.f90
@@ -0,0 +1,101 @@
+!
+!
+!                             AMG4PSBLAS version 1.0
+!    Algebraic Multigrid Package
+!               based on PSBLAS (Parallel Sparse BLAS version 3.7)
+!
+!    (C) Copyright 2021
+!
+!        Salvatore Filippone
+!        Pasqua D'Ambra
+!        Fabio Durastante
+!
+!    Redistribution and use in source and binary forms, with or without
+!    modification, are permitted provided that the following conditions
+!    are met:
+!      1. Redistributions of source code must retain the above copyright
+!         notice, this list of conditions and the following disclaimer.
+!      2. Redistributions in binary form must reproduce the above copyright
+!         notice, this list of conditions, and the following disclaimer in the
+!         documentation and/or other materials provided with the distribution.
+!      3. The name of the AMG4PSBLAS group or the names of its contributors may
+!         not be used to endorse or promote products derived from this
+!         software without specific written permission.
+!
+!    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+!    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+!    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+!    PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AMG4PSBLAS GROUP OR ITS CONTRIBUTORS
+!    BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+!    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+!    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+!    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+!    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+!    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+!    POSSIBILITY OF SUCH DAMAGE.
+!
+module amg_d_pde3d_box_mod
+  use psb_base_mod, only : psb_dpk_, done, dzero
+  real(psb_dpk_), save, private :: epsilon=done/80
+contains
+  subroutine pde_set_parm3d_box(dat)
+    real(psb_dpk_), intent(in) :: dat
+    epsilon = dat
+  end subroutine pde_set_parm3d_box
+  !
+  ! functions parametrizing the differential equation
+  !
+  function b1_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) :: b1_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    b1_box=done/sqrt(3.0_psb_dpk_)
+  end function b1_box
+  function b2_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) ::  b2_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    b2_box=done/sqrt(3.0_psb_dpk_)
+  end function b2_box
+  function b3_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) ::  b3_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    b3_box=done/sqrt(3.0_psb_dpk_)
+  end function b3_box
+  function c_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) ::  c_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    c_box=dzero
+  end function c_box
+  function a1_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) ::  a1_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    a1_box=epsilon
+  end function a1_box
+  function a2_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) ::  a2_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    a2_box=epsilon
+  end function a2_box
+  function a3_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) ::  a3_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    a3_box=epsilon
+  end function a3_box
+  function g_box(x,y,z)
+    implicit none 
+    real(psb_dpk_) ::  g_box
+    real(psb_dpk_), intent(in) :: x,y,z
+    g_box= dzero
+    if (x == done) then
+      g_box = done
+    else if (x == dzero) then
+      g_box = done
+    end if
+  end function g_box
+end module amg_d_pde3d_box_mod
diff --git a/samples/advanced/pdegen/amg_d_pde3d_exp_mod.f90 b/samples/advanced/pdegen/amg_d_pde3d_exp_mod.f90
index e7bcf6ef..fea3b8a4 100644
--- a/samples/advanced/pdegen/amg_d_pde3d_exp_mod.f90
+++ b/samples/advanced/pdegen/amg_d_pde3d_exp_mod.f90
@@ -38,10 +38,10 @@ module amg_d_pde3d_exp_mod
   use psb_base_mod, only : psb_dpk_, done, dzero
   real(psb_dpk_), save, private :: epsilon=done/160
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm3d_exp(dat)
     real(psb_dpk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm3d_exp
   !
   ! functions parametrizing the differential equation
   !
diff --git a/samples/advanced/pdegen/amg_d_pde3d_gauss_mod.f90 b/samples/advanced/pdegen/amg_d_pde3d_gauss_mod.f90
index 8dd5f71a..c2403131 100644
--- a/samples/advanced/pdegen/amg_d_pde3d_gauss_mod.f90
+++ b/samples/advanced/pdegen/amg_d_pde3d_gauss_mod.f90
@@ -38,10 +38,10 @@ module amg_d_pde3d_gauss_mod
   use psb_base_mod, only : psb_dpk_, done, dzero
   real(psb_dpk_), save, private :: epsilon=done/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm3d_gauss(dat)
     real(psb_dpk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm3d_gauss
   !
   ! functions parametrizing the differential equation
   !
diff --git a/samples/advanced/pdegen/amg_s_pde2d.F90 b/samples/advanced/pdegen/amg_s_pde2d.F90
index f3842a65..3d631a06 100644
--- a/samples/advanced/pdegen/amg_s_pde2d.F90
+++ b/samples/advanced/pdegen/amg_s_pde2d.F90
@@ -72,6 +72,7 @@ program amg_s_pde2d
   use amg_s_pde2d_base_mod
   use amg_s_pde2d_exp_mod
   use amg_s_pde2d_box_mod
+  use amg_s_pde2d_gauss_mod
   use amg_s_genpde_mod
 #if defined(OPENMP)
   use omp_lib
@@ -124,16 +125,16 @@ program amg_s_pde2d
     integer(psb_ipk_)  :: outer_sweeps ! number of outer sweeps: sweeps for 1-level,
     ! AMG cycles for ML
     ! general AMG data
-    character(len=16)  :: mlcycle      ! AMG cycle type
+    character(len=32)  :: mlcycle      ! AMG cycle type
     integer(psb_ipk_)  :: maxlevs     ! maximum number of levels in AMG preconditioner
 
     ! AMG aggregation
-    character(len=16)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
-    character(len=16)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
-    character(len=16)  :: aggr_type   ! Type of aggregation SOC1, SOC2, MATCHBOXP
+    character(len=32)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
+    character(len=32)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
+    character(len=32)  :: aggr_type   ! Type of aggregation SOC1, SOC2, MATCHBOXP
     integer(psb_ipk_)  :: aggr_size   ! Requested size of the aggregates for MATCHBOXP
-    character(len=16)  :: aggr_ord    ! ordering for aggregation: NATURAL, DEGREE
-    character(len=16)  :: aggr_filter ! filtering: FILTER, NO_FILTER
+    character(len=32)  :: aggr_ord    ! ordering for aggregation: NATURAL, DEGREE
+    character(len=32)  :: aggr_filter ! filtering: FILTER, NO_FILTER
     real(psb_spk_)     :: mncrratio  ! minimum aggregation ratio
     real(psb_spk_), allocatable :: athresv(:) ! smoothed aggregation threshold vector
     integer(psb_ipk_)  :: thrvsz      ! size of threshold vector
@@ -141,39 +142,39 @@ program amg_s_pde2d
     integer(psb_ipk_)  :: csizepp     ! minimum size of coarsest matrix per process
 
     ! AMG smoother or pre-smoother; also 1-lev preconditioner
-    character(len=16)  :: smther       ! (pre-)smoother type: BJAC, AS
+    character(len=32)  :: smther       ! (pre-)smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps      ! (pre-)smoother / 1-lev prec. sweeps
     integer(psb_ipk_)  :: novr         ! number of overlap layers
-    character(len=16)  :: restr        ! restriction over application of AS
-    character(len=16)  :: prol         ! prolongation over application of AS
-    character(len=16)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr        ! restriction over application of AS
+    character(len=32)  :: prol         ! prolongation over application of AS
+    character(len=32)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps      ! inner solver sweeps
-    character(len=16)  :: variant      ! AINV variant: LLK, etc
+    character(len=32)  :: variant      ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill         ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill      ! Inverse fill-in for INVK
     real(psb_spk_)      :: thr          ! threshold for ILUT factorization
 
     ! AMG post-smoother; ignored by 1-lev preconditioner
-    character(len=16)  :: smther2      ! post-smoother type: BJAC, AS
+    character(len=32)  :: smther2      ! post-smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps2     ! post-smoother sweeps
     integer(psb_ipk_)  :: novr2        ! number of overlap layers
-    character(len=16)  :: restr2       ! restriction  over application of AS
-    character(len=16)  :: prol2        ! prolongation over application of AS
-    character(len=16)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr2       ! restriction  over application of AS
+    character(len=32)  :: prol2        ! prolongation over application of AS
+    character(len=32)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps2     ! inner solver sweeps
-    character(len=16)  :: variant2     ! AINV variant: LLK, etc
+    character(len=32)  :: variant2     ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill2        ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill2     ! Inverse fill-in for INVK
     real(psb_spk_)      :: thr2         ! threshold for ILUT factorization
 
     ! coarsest-level solver
-    character(len=16)  :: cmat        ! coarsest matrix layout: REPL, DIST
-    character(len=16)  :: csolve      ! coarsest-lev solver: BJAC, SLUDIST (distr.
+    character(len=32)  :: cmat        ! coarsest matrix layout: REPL, DIST
+    character(len=32)  :: csolve      ! coarsest-lev solver: BJAC, SLUDIST (distr.
                                       ! mat.); UMF, MUMPS, SLU, ILU, ILUT, MILU
                                       ! (repl. mat.)
-    character(len=16)  :: csbsolve    ! coarsest-lev local subsolver: ILU, ILUT,
+    character(len=32)  :: csbsolve    ! coarsest-lev local subsolver: ILU, ILUT,
                                       ! MILU, UMF, MUMPS, SLU
     integer(psb_ipk_)  :: cfill       ! fill-in for incomplete LU factorization
     real(psb_spk_)     :: cthres      ! threshold for ILUT factorization
@@ -241,13 +242,16 @@ program amg_s_pde2d
   select case(psb_toupper(trim(pdecoeff)))
   case("CONST")
     call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
-        & a1,a2,b1,b2,c,g,info)
+        & a1_base,a2_base,b1_base,b2_base,c_base,g_base,info)
   case("EXP")
     call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_exp,a2_exp,b1_exp,b2_exp,c_exp,g_exp,info)
   case("BOX")
     call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_box,a2_box,b1_box,b2_box,c_box,g_box,info)
+  case("GAUSS")
+    call amg_gen_pde2d(ctxt,idim,a,b,x,desc_a,afmt,&
+        & a1_gauss,a2_gauss,b1_gauss,b2_gauss,c_gauss,g_gauss,info)
   case default
     info=psb_err_from_subroutine_
     ch_err='amg_gen_pdecoeff'
diff --git a/samples/advanced/pdegen/amg_s_pde2d_base_mod.f90 b/samples/advanced/pdegen/amg_s_pde2d_base_mod.f90
index 462c6154..d5cbc6d0 100644
--- a/samples/advanced/pdegen/amg_s_pde2d_base_mod.f90
+++ b/samples/advanced/pdegen/amg_s_pde2d_base_mod.f90
@@ -38,52 +38,52 @@ module amg_s_pde2d_base_mod
   use psb_base_mod, only : psb_spk_, szero, sone
   real(psb_spk_), save, private :: epsilon=sone/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm2d_base(dat)
     real(psb_spk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm2d_base
   !
   ! functions parametrizing the differential equation
   !
-  function b1(x,y)
+  function b1_base(x,y)
     implicit none 
-    real(psb_spk_) :: b1
+    real(psb_spk_) :: b1_base
     real(psb_spk_), intent(in) :: x,y
-    b1 = szero/1.414_psb_spk_
-  end function b1
-  function b2(x,y)
+    b1_base = szero/1.414_psb_spk_
+  end function b1_base
+  function b2_base(x,y)
     implicit none 
-    real(psb_spk_) ::  b2
+    real(psb_spk_) ::  b2_base
     real(psb_spk_), intent(in) :: x,y
-    b2 = szero/1.414_psb_spk_
-  end function b2
-  function c(x,y)
+    b2_base = szero/1.414_psb_spk_
+  end function b2_base
+  function c_base(x,y)
     implicit none 
-    real(psb_spk_) ::  c
+    real(psb_spk_) ::  c_base
     real(psb_spk_), intent(in) :: x,y
-    c = szero
-  end function c
-  function a1(x,y)
+    c_base = szero
+  end function c_base
+  function a1_base(x,y)
     implicit none 
-    real(psb_spk_) ::  a1
+    real(psb_spk_) ::  a1_base
     real(psb_spk_), intent(in) :: x,y
-    a1=sone*epsilon
-  end function a1
-  function a2(x,y)
+    a1_base=sone*epsilon
+  end function a1_base
+  function a2_base(x,y)
     implicit none 
-    real(psb_spk_) ::  a2
+    real(psb_spk_) ::  a2_base
     real(psb_spk_), intent(in) :: x,y
-    a2=sone*epsilon
-  end function a2
-  function g(x,y)
+    a2_base=sone*epsilon
+  end function a2_base
+  function g_base(x,y)
     implicit none 
-    real(psb_spk_) ::  g
+    real(psb_spk_) ::  g_base
     real(psb_spk_), intent(in) :: x,y
-    g = szero
+    g_base = szero
     if (x == sone) then
-      g = sone
+      g_base = sone
     else if (x == szero) then
-      g = sone
+      g_base = sone
     end if
-  end function g
+  end function g_base
 end module amg_s_pde2d_base_mod
diff --git a/samples/advanced/pdegen/amg_s_pde2d_box_mod.f90 b/samples/advanced/pdegen/amg_s_pde2d_box_mod.f90
index 9183521b..c36f8eb0 100644
--- a/samples/advanced/pdegen/amg_s_pde2d_box_mod.f90
+++ b/samples/advanced/pdegen/amg_s_pde2d_box_mod.f90
@@ -38,10 +38,10 @@ module amg_s_pde2d_box_mod
   use psb_base_mod, only : psb_spk_, szero, sone
   real(psb_spk_), save, private :: epsilon=sone/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm2d_box(dat)
     real(psb_spk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm2d_box
   !
   ! functions parametrizing the differential equation
   !
diff --git a/samples/advanced/pdegen/amg_s_pde2d_exp_mod.f90 b/samples/advanced/pdegen/amg_s_pde2d_exp_mod.f90
index 3657546d..acc786b2 100644
--- a/samples/advanced/pdegen/amg_s_pde2d_exp_mod.f90
+++ b/samples/advanced/pdegen/amg_s_pde2d_exp_mod.f90
@@ -38,10 +38,10 @@ module amg_s_pde2d_exp_mod
   use psb_base_mod, only : psb_spk_, sone, szero
   real(psb_spk_), save, private :: epsilon=sone/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm2d_exp(dat)
     real(psb_spk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm2d_exp
   !
   ! functions parametrizing the differential equation
   !
diff --git a/samples/advanced/pdegen/amg_s_pde2d_gauss_mod.f90 b/samples/advanced/pdegen/amg_s_pde2d_gauss_mod.f90
new file mode 100644
index 00000000..dd234d66
--- /dev/null
+++ b/samples/advanced/pdegen/amg_s_pde2d_gauss_mod.f90
@@ -0,0 +1,89 @@
+!
+!
+!                             AMG4PSBLAS version 1.0
+!    Algebraic Multigrid Package
+!               based on PSBLAS (Parallel Sparse BLAS version 3.7)
+!
+!    (C) Copyright 2021
+!
+!        Salvatore Filippone
+!        Pasqua D'Ambra
+!        Fabio Durastante
+!
+!    Redistribution and use in source and binary forms, with or without
+!    modification, are permitted provided that the following conditions
+!    are met:
+!      1. Redistributions of source code must retain the above copyright
+!         notice, this list of conditions and the following disclaimer.
+!      2. Redistributions in binary form must reproduce the above copyright
+!         notice, this list of conditions, and the following disclaimer in the
+!         documentation and/or other materials provided with the distribution.
+!      3. The name of the AMG4PSBLAS group or the names of its contributors may
+!         not be used to endorse or promote products derived from this
+!         software without specific written permission.
+!
+!    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+!    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+!    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+!    PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AMG4PSBLAS GROUP OR ITS CONTRIBUTORS
+!    BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+!    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+!    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+!    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+!    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+!    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+!    POSSIBILITY OF SUCH DAMAGE.
+!
+module amg_s_pde2d_gauss_mod
+  use psb_base_mod, only : psb_spk_, sone, szero
+  real(psb_spk_), save, private :: epsilon=sone/80
+contains
+  subroutine pde_set_parm2d_gauss(dat)
+    real(psb_spk_), intent(in) :: dat
+    epsilon = dat
+  end subroutine pde_set_parm2d_gauss
+  !
+  ! functions parametrizing the differential equation
+  !
+  function b1_gauss(x,y)
+    implicit none 
+    real(psb_spk_) :: b1_gauss
+    real(psb_spk_), intent(in) :: x,y
+    b1_gauss=sone/sqrt(3.0_psb_spk_)-2*x*exp(-(x**2+y**2))
+  end function b1_gauss
+  function b2_gauss(x,y)
+    implicit none 
+    real(psb_spk_) ::  b2_gauss
+    real(psb_spk_), intent(in) :: x,y
+    b2_gauss=sone/sqrt(3.0_psb_spk_)-2*y*exp(-(x**2+y**2))
+  end function b2_gauss
+  function c_gauss(x,y)
+    implicit none 
+    real(psb_spk_) ::  c_gauss
+    real(psb_spk_), intent(in) :: x,y
+    c_gauss=szero
+  end function c_gauss
+  function a1_gauss(x,y)
+    implicit none 
+    real(psb_spk_) ::  a1_gauss
+    real(psb_spk_), intent(in) :: x,y
+    a1_gauss=epsilon*exp(-(x**2+y**2))
+  end function a1_gauss
+  function a2_gauss(x,y)
+    implicit none 
+    real(psb_spk_) ::  a2_gauss
+    real(psb_spk_), intent(in) :: x,y
+    a2_gauss=epsilon*exp(-(x**2+y**2))
+  end function a2_gauss
+  function g_gauss(x,y)
+    implicit none 
+    real(psb_spk_) ::  g_gauss
+    real(psb_spk_), intent(in) :: x,y
+    g_gauss = szero
+    if (x == sone) then
+      g_gauss = sone
+    else if (x == szero) then
+      g_gauss = sone
+    end if
+  end function g_gauss
+end module amg_s_pde2d_gauss_mod
diff --git a/samples/advanced/pdegen/amg_s_pde3d.F90 b/samples/advanced/pdegen/amg_s_pde3d.F90
index 97abad28..0b495670 100644
--- a/samples/advanced/pdegen/amg_s_pde3d.F90
+++ b/samples/advanced/pdegen/amg_s_pde3d.F90
@@ -72,6 +72,7 @@ program amg_s_pde3d
   use data_input
   use amg_s_pde3d_base_mod
   use amg_s_pde3d_exp_mod
+  use amg_s_pde3d_box_mod
   use amg_s_pde3d_gauss_mod
   use amg_s_genpde_mod
 #if defined(OPENMP)
@@ -125,16 +126,16 @@ program amg_s_pde3d
     integer(psb_ipk_)  :: outer_sweeps ! number of outer sweeps: sweeps for 1-level,
     ! AMG cycles for ML
     ! general AMG data
-    character(len=16)  :: mlcycle      ! AMG cycle type
+    character(len=32)  :: mlcycle      ! AMG cycle type
     integer(psb_ipk_)  :: maxlevs      ! maximum number of levels in AMG preconditioner
 
     ! AMG aggregation
-    character(len=16)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
-    character(len=16)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
-    character(len=16)  :: aggr_type    ! Type of aggregation SOC1, SOC2, MATCHBOXP
+    character(len=32)  :: aggr_prol    ! aggregation type: SMOOTHED, NONSMOOTHED
+    character(len=32)  :: par_aggr_alg ! parallel aggregation algorithm: DEC, SYMDEC
+    character(len=32)  :: aggr_type    ! Type of aggregation SOC1, SOC2, MATCHBOXP
     integer(psb_ipk_)  :: aggr_size    ! Requested size of the aggregates for MATCHBOXP
-    character(len=16)  :: aggr_ord     ! ordering for aggregation: NATURAL, DEGREE
-    character(len=16)  :: aggr_filter  ! filtering: FILTER, NO_FILTER
+    character(len=32)  :: aggr_ord     ! ordering for aggregation: NATURAL, DEGREE
+    character(len=32)  :: aggr_filter  ! filtering: FILTER, NO_FILTER
     real(psb_spk_)      :: mncrratio    ! minimum aggregation ratio
     real(psb_spk_), allocatable :: athresv(:) ! smoothed aggregation threshold vector
     integer(psb_ipk_)  :: thrvsz       ! size of threshold vector
@@ -142,39 +143,39 @@ program amg_s_pde3d
     integer(psb_ipk_)  :: csizepp      ! minimum size of coarsest matrix per process
 
     ! AMG smoother or pre-smoother; also 1-lev preconditioner
-    character(len=16)  :: smther       ! (pre-)smoother type: BJAC, AS
+    character(len=32)  :: smther       ! (pre-)smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps      ! (pre-)smoother / 1-lev prec. sweeps
     integer(psb_ipk_)  :: novr         ! number of overlap layers
-    character(len=16)  :: restr        ! restriction over application of AS
-    character(len=16)  :: prol         ! prolongation over application of AS
-    character(len=16)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr        ! restriction over application of AS
+    character(len=32)  :: prol         ! prolongation over application of AS
+    character(len=32)  :: solve        ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps      ! inner solver sweeps
-    character(len=16)  :: variant      ! AINV variant: LLK, etc
+    character(len=32)  :: variant      ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill         ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill      ! Inverse fill-in for INVK
     real(psb_spk_)      :: thr          ! threshold for ILUT factorization
 
     ! AMG post-smoother; ignored by 1-lev preconditioner
-    character(len=16)  :: smther2      ! post-smoother type: BJAC, AS
+    character(len=32)  :: smther2      ! post-smoother type: BJAC, AS
     integer(psb_ipk_)  :: jsweeps2     ! post-smoother sweeps
     integer(psb_ipk_)  :: novr2        ! number of overlap layers
-    character(len=16)  :: restr2       ! restriction  over application of AS
-    character(len=16)  :: prol2        ! prolongation over application of AS
-    character(len=16)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
+    character(len=32)  :: restr2       ! restriction  over application of AS
+    character(len=32)  :: prol2        ! prolongation over application of AS
+    character(len=32)  :: solve2       ! local subsolver type: ILU, MILU, ILUT,
                                        ! UMF, MUMPS, SLU, FWGS, BWGS, JAC
     integer(psb_ipk_)  :: ssweeps2     ! inner solver sweeps
-    character(len=16)  :: variant2     ! AINV variant: LLK, etc
+    character(len=32)  :: variant2     ! AINV variant: LLK, etc
     integer(psb_ipk_)  :: fill2        ! fill-in for incomplete LU factorization
     integer(psb_ipk_)  :: invfill2     ! Inverse fill-in for INVK
     real(psb_spk_)      :: thr2         ! threshold for ILUT factorization
 
     ! coarsest-level solver
-    character(len=16)  :: cmat         ! coarsest matrix layout: REPL, DIST
-    character(len=16)  :: csolve       ! coarsest-lev solver: BJAC, SLUDIST (distr.
+    character(len=32)  :: cmat         ! coarsest matrix layout: REPL, DIST
+    character(len=32)  :: csolve       ! coarsest-lev solver: BJAC, SLUDIST (distr.
                                        ! mat.); UMF, MUMPS, SLU, ILU, ILUT, MILU
                                        ! (repl. mat.)
-    character(len=16)  :: csbsolve     ! coarsest-lev local subsolver: ILU, ILUT,
+    character(len=32)  :: csbsolve     ! coarsest-lev local subsolver: ILU, ILUT,
                                        ! MILU, UMF, MUMPS, SLU
     integer(psb_ipk_)  :: cfill        ! fill-in for incomplete LU factorization
     real(psb_spk_)     :: cthres        ! threshold for ILUT factorization
@@ -243,10 +244,13 @@ program amg_s_pde3d
   select case(psb_toupper(trim(pdecoeff)))
   case("CONST")
     call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
-        & a1,a2,a3,b1,b2,b3,c,g,info)
+        & a1_base,a2_base,a3_base,b1_base,b2_base,b3_base,c_base,g_base,info)
   case("EXP")
     call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_exp,a2_exp,a3_exp,b1_exp,b2_exp,b3_exp,c_exp,g_exp,info)
+  case("BOX")
+    call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
+        & a1_box,a2_box,a3_box,b1_box,b2_box,b3_box,c_box,g_box,info)
   case("GAUSS")
     call amg_gen_pde3d(ctxt,idim,a,b,x,desc_a,afmt,&
         & a1_gauss,a2_gauss,a3_gauss,b1_gauss,b2_gauss,b3_gauss,c_gauss,g_gauss,info)
diff --git a/samples/advanced/pdegen/amg_s_pde3d_base_mod.f90 b/samples/advanced/pdegen/amg_s_pde3d_base_mod.f90
index 0ce83989..3dbd039f 100644
--- a/samples/advanced/pdegen/amg_s_pde3d_base_mod.f90
+++ b/samples/advanced/pdegen/amg_s_pde3d_base_mod.f90
@@ -38,64 +38,64 @@ module amg_s_pde3d_base_mod
   use psb_base_mod, only : psb_spk_, sone, szero
   real(psb_spk_), save, private :: epsilon=sone/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm3d_base(dat)
     real(psb_spk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm3d_base
   !
   ! functions parametrizing the differential equation
   !
-  function b1(x,y,z)
+  function b1_base(x,y,z)
     implicit none 
-    real(psb_spk_) :: b1
+    real(psb_spk_) :: b1_base
     real(psb_spk_), intent(in) :: x,y,z
-    b1=sone/sqrt(3.0_psb_spk_)
-  end function b1
-  function b2(x,y,z)
+    b1_base=szero/sqrt(3.0_psb_spk_)
+  end function b1_base
+  function b2_base(x,y,z)
     implicit none 
-    real(psb_spk_) ::  b2
+    real(psb_spk_) ::  b2_base
     real(psb_spk_), intent(in) :: x,y,z
-    b2=sone/sqrt(3.0_psb_spk_)
-  end function b2
-  function b3(x,y,z)
+    b2_base=szero/sqrt(3.0_psb_spk_)
+  end function b2_base
+  function b3_base(x,y,z)
     implicit none 
-    real(psb_spk_) ::  b3
+    real(psb_spk_) ::  b3_base
     real(psb_spk_), intent(in) :: x,y,z
-    b3=sone/sqrt(3.0_psb_spk_)
-  end function b3
-  function c(x,y,z)
+    b3_base=szero/sqrt(3.0_psb_spk_)
+  end function b3_base
+  function c_base(x,y,z)
     implicit none 
-    real(psb_spk_) ::  c
+    real(psb_spk_) ::  c_base
     real(psb_spk_), intent(in) :: x,y,z
-    c=szero
-  end function c
-  function a1(x,y,z)
+    c_base=szero
+  end function c_base
+  function a1_base(x,y,z)
     implicit none 
-    real(psb_spk_) ::  a1
+    real(psb_spk_) ::  a1_base
     real(psb_spk_), intent(in) :: x,y,z
-    a1=epsilon
-  end function a1
-  function a2(x,y,z)
+    a1_base=epsilon
+  end function a1_base
+  function a2_base(x,y,z)
     implicit none 
-    real(psb_spk_) ::  a2
+    real(psb_spk_) ::  a2_base
     real(psb_spk_), intent(in) :: x,y,z
-    a2=epsilon
-  end function a2
-  function a3(x,y,z)
+    a2_base=epsilon
+  end function a2_base
+  function a3_base(x,y,z)
     implicit none 
-    real(psb_spk_) ::  a3
+    real(psb_spk_) ::  a3_base
     real(psb_spk_), intent(in) :: x,y,z
-    a3=epsilon
-  end function a3
-  function g(x,y,z)
+    a3_base=epsilon
+  end function a3_base
+  function g_base(x,y,z)
     implicit none 
-    real(psb_spk_) ::  g
+    real(psb_spk_) ::  g_base
     real(psb_spk_), intent(in) :: x,y,z
-    g = szero
+    g_base = szero
     if (x == sone) then
-      g = sone
+      g_base = sone
     else if (x == szero) then
-      g = sone
+      g_base = sone
     end if
-  end function g
+  end function g_base
 end module amg_s_pde3d_base_mod
diff --git a/samples/advanced/pdegen/amg_s_pde3d_box_mod.f90 b/samples/advanced/pdegen/amg_s_pde3d_box_mod.f90
new file mode 100644
index 00000000..e0a1a5e3
--- /dev/null
+++ b/samples/advanced/pdegen/amg_s_pde3d_box_mod.f90
@@ -0,0 +1,101 @@
+!
+!
+!                             AMG4PSBLAS version 1.0
+!    Algebraic Multigrid Package
+!               based on PSBLAS (Parallel Sparse BLAS version 3.7)
+!
+!    (C) Copyright 2021
+!
+!        Salvatore Filippone
+!        Pasqua D'Ambra
+!        Fabio Durastante
+!
+!    Redistribution and use in source and binary forms, with or without
+!    modification, are permitted provided that the following conditions
+!    are met:
+!      1. Redistributions of source code must retain the above copyright
+!         notice, this list of conditions and the following disclaimer.
+!      2. Redistributions in binary form must reproduce the above copyright
+!         notice, this list of conditions, and the following disclaimer in the
+!         documentation and/or other materials provided with the distribution.
+!      3. The name of the AMG4PSBLAS group or the names of its contributors may
+!         not be used to endorse or promote products derived from this
+!         software without specific written permission.
+!
+!    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+!    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+!    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+!    PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AMG4PSBLAS GROUP OR ITS CONTRIBUTORS
+!    BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+!    CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+!    SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+!    INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+!    CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+!    ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+!    POSSIBILITY OF SUCH DAMAGE.
+!
+module amg_s_pde3d_box_mod
+  use psb_base_mod, only : psb_spk_, sone, szero
+  real(psb_spk_), save, private :: epsilon=sone/80
+contains
+  subroutine pde_set_parm3d_box(dat)
+    real(psb_spk_), intent(in) :: dat
+    epsilon = dat
+  end subroutine pde_set_parm3d_box
+  !
+  ! functions parametrizing the differential equation
+  !
+  function b1_box(x,y,z)
+    implicit none 
+    real(psb_spk_) :: b1_box
+    real(psb_spk_), intent(in) :: x,y,z
+    b1_box=sone/sqrt(3.0_psb_spk_)
+  end function b1_box
+  function b2_box(x,y,z)
+    implicit none 
+    real(psb_spk_) ::  b2_box
+    real(psb_spk_), intent(in) :: x,y,z
+    b2_box=sone/sqrt(3.0_psb_spk_)
+  end function b2_box
+  function b3_box(x,y,z)
+    implicit none 
+    real(psb_spk_) ::  b3_box
+    real(psb_spk_), intent(in) :: x,y,z
+    b3_box=sone/sqrt(3.0_psb_spk_)
+  end function b3_box
+  function c_box(x,y,z)
+    implicit none 
+    real(psb_spk_) ::  c_box
+    real(psb_spk_), intent(in) :: x,y,z
+    c_box=szero
+  end function c_box
+  function a1_box(x,y,z)
+    implicit none 
+    real(psb_spk_) ::  a1_box
+    real(psb_spk_), intent(in) :: x,y,z
+    a1_box=epsilon
+  end function a1_box
+  function a2_box(x,y,z)
+    implicit none 
+    real(psb_spk_) ::  a2_box
+    real(psb_spk_), intent(in) :: x,y,z
+    a2_box=epsilon
+  end function a2_box
+  function a3_box(x,y,z)
+    implicit none 
+    real(psb_spk_) ::  a3_box
+    real(psb_spk_), intent(in) :: x,y,z
+    a3_box=epsilon
+  end function a3_box
+  function g_box(x,y,z)
+    implicit none 
+    real(psb_spk_) ::  g_box
+    real(psb_spk_), intent(in) :: x,y,z
+    g_box= szero
+    if (x == sone) then
+      g_box = sone
+    else if (x == szero) then
+      g_box = sone
+    end if
+  end function g_box
+end module amg_s_pde3d_box_mod
diff --git a/samples/advanced/pdegen/amg_s_pde3d_exp_mod.f90 b/samples/advanced/pdegen/amg_s_pde3d_exp_mod.f90
index 8ec96d00..d1f8fbea 100644
--- a/samples/advanced/pdegen/amg_s_pde3d_exp_mod.f90
+++ b/samples/advanced/pdegen/amg_s_pde3d_exp_mod.f90
@@ -38,10 +38,10 @@ module amg_s_pde3d_exp_mod
   use psb_base_mod, only : psb_spk_, sone, szero
   real(psb_spk_), save, private :: epsilon=sone/160
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm3d_exp(dat)
     real(psb_spk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm3d_exp
   !
   ! functions parametrizing the differential equation
   !
diff --git a/samples/advanced/pdegen/amg_s_pde3d_gauss_mod.f90 b/samples/advanced/pdegen/amg_s_pde3d_gauss_mod.f90
index fa6362e0..d7bb81ab 100644
--- a/samples/advanced/pdegen/amg_s_pde3d_gauss_mod.f90
+++ b/samples/advanced/pdegen/amg_s_pde3d_gauss_mod.f90
@@ -38,10 +38,10 @@ module amg_s_pde3d_gauss_mod
   use psb_base_mod, only : psb_spk_, sone, szero
   real(psb_spk_), save, private :: epsilon=sone/80
 contains
-  subroutine pde_set_parm(dat)
+  subroutine pde_set_parm3d_gauss(dat)
     real(psb_spk_), intent(in) :: dat
     epsilon = dat
-  end subroutine pde_set_parm
+  end subroutine pde_set_parm3d_gauss
   !
   ! functions parametrizing the differential equation
   !