diff --git a/base/modules/serial/psb_c_mat_mod.F90 b/base/modules/serial/psb_c_mat_mod.F90
index ee819535..e7c84b00 100644
--- a/base/modules/serial/psb_c_mat_mod.F90
+++ b/base/modules/serial/psb_c_mat_mod.F90
@@ -205,6 +205,7 @@ module psb_c_mat_mod
     procedure, pass(a) :: cscnv_base  => psb_c_cscnv_base
     generic, public    :: cscnv       => cscnv_np, cscnv_ip, cscnv_base
     procedure, pass(a) :: split_nd    => psb_c_split_nd
+    procedure, pass(a) :: merge_nd    => psb_c_merge_nd
     procedure, pass(a) :: clone       => psb_cspmat_clone
     procedure, pass(a) :: move_alloc  => psb_cspmat_type_move
     !
@@ -849,11 +850,17 @@ module psb_c_mat_mod
       class(psb_cspmat_type), intent(inout) :: a
       integer(psb_ipk_), intent(in)           :: n_rows, n_cols
       integer(psb_ipk_), intent(out)          :: info
-!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
-!!$      character(len=*), optional, intent(in) :: type
-!!$      class(psb_c_base_sparse_mat), intent(in), optional :: mold
     end subroutine psb_c_split_nd
   end interface
+  
+  interface
+    subroutine psb_c_merge_nd(a,n_rows,n_cols,info)
+      import :: psb_ipk_, psb_lpk_, psb_cspmat_type, psb_spk_, psb_c_base_sparse_mat
+      class(psb_cspmat_type), intent(inout) :: a
+      integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+      integer(psb_ipk_), intent(out)          :: info
+    end subroutine psb_c_merge_nd
+  end interface
 
   !
   ! CSCNV: switches to a different internal derived type.
diff --git a/base/modules/serial/psb_d_mat_mod.F90 b/base/modules/serial/psb_d_mat_mod.F90
index 82d2e822..fe09d83a 100644
--- a/base/modules/serial/psb_d_mat_mod.F90
+++ b/base/modules/serial/psb_d_mat_mod.F90
@@ -205,6 +205,7 @@ module psb_d_mat_mod
     procedure, pass(a) :: cscnv_base  => psb_d_cscnv_base
     generic, public    :: cscnv       => cscnv_np, cscnv_ip, cscnv_base
     procedure, pass(a) :: split_nd    => psb_d_split_nd
+    procedure, pass(a) :: merge_nd    => psb_d_merge_nd
     procedure, pass(a) :: clone       => psb_dspmat_clone
     procedure, pass(a) :: move_alloc  => psb_dspmat_type_move
     !
@@ -849,11 +850,17 @@ module psb_d_mat_mod
       class(psb_dspmat_type), intent(inout) :: a
       integer(psb_ipk_), intent(in)           :: n_rows, n_cols
       integer(psb_ipk_), intent(out)          :: info
-!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
-!!$      character(len=*), optional, intent(in) :: type
-!!$      class(psb_d_base_sparse_mat), intent(in), optional :: mold
     end subroutine psb_d_split_nd
   end interface
+  
+  interface
+    subroutine psb_d_merge_nd(a,n_rows,n_cols,info)
+      import :: psb_ipk_, psb_lpk_, psb_dspmat_type, psb_dpk_, psb_d_base_sparse_mat
+      class(psb_dspmat_type), intent(inout) :: a
+      integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+      integer(psb_ipk_), intent(out)          :: info
+    end subroutine psb_d_merge_nd
+  end interface
 
   !
   ! CSCNV: switches to a different internal derived type.
diff --git a/base/modules/serial/psb_s_mat_mod.F90 b/base/modules/serial/psb_s_mat_mod.F90
index d8a2e6ae..868583b2 100644
--- a/base/modules/serial/psb_s_mat_mod.F90
+++ b/base/modules/serial/psb_s_mat_mod.F90
@@ -205,6 +205,7 @@ module psb_s_mat_mod
     procedure, pass(a) :: cscnv_base  => psb_s_cscnv_base
     generic, public    :: cscnv       => cscnv_np, cscnv_ip, cscnv_base
     procedure, pass(a) :: split_nd    => psb_s_split_nd
+    procedure, pass(a) :: merge_nd    => psb_s_merge_nd
     procedure, pass(a) :: clone       => psb_sspmat_clone
     procedure, pass(a) :: move_alloc  => psb_sspmat_type_move
     !
@@ -849,11 +850,17 @@ module psb_s_mat_mod
       class(psb_sspmat_type), intent(inout) :: a
       integer(psb_ipk_), intent(in)           :: n_rows, n_cols
       integer(psb_ipk_), intent(out)          :: info
-!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
-!!$      character(len=*), optional, intent(in) :: type
-!!$      class(psb_s_base_sparse_mat), intent(in), optional :: mold
     end subroutine psb_s_split_nd
   end interface
+  
+  interface
+    subroutine psb_s_merge_nd(a,n_rows,n_cols,info)
+      import :: psb_ipk_, psb_lpk_, psb_sspmat_type, psb_spk_, psb_s_base_sparse_mat
+      class(psb_sspmat_type), intent(inout) :: a
+      integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+      integer(psb_ipk_), intent(out)          :: info
+    end subroutine psb_s_merge_nd
+  end interface
 
   !
   ! CSCNV: switches to a different internal derived type.
diff --git a/base/modules/serial/psb_z_mat_mod.F90 b/base/modules/serial/psb_z_mat_mod.F90
index 694d4efc..48b670de 100644
--- a/base/modules/serial/psb_z_mat_mod.F90
+++ b/base/modules/serial/psb_z_mat_mod.F90
@@ -205,6 +205,7 @@ module psb_z_mat_mod
     procedure, pass(a) :: cscnv_base  => psb_z_cscnv_base
     generic, public    :: cscnv       => cscnv_np, cscnv_ip, cscnv_base
     procedure, pass(a) :: split_nd    => psb_z_split_nd
+    procedure, pass(a) :: merge_nd    => psb_z_merge_nd
     procedure, pass(a) :: clone       => psb_zspmat_clone
     procedure, pass(a) :: move_alloc  => psb_zspmat_type_move
     !
@@ -849,11 +850,17 @@ module psb_z_mat_mod
       class(psb_zspmat_type), intent(inout) :: a
       integer(psb_ipk_), intent(in)           :: n_rows, n_cols
       integer(psb_ipk_), intent(out)          :: info
-!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
-!!$      character(len=*), optional, intent(in) :: type
-!!$      class(psb_z_base_sparse_mat), intent(in), optional :: mold
     end subroutine psb_z_split_nd
   end interface
+  
+  interface
+    subroutine psb_z_merge_nd(a,n_rows,n_cols,info)
+      import :: psb_ipk_, psb_lpk_, psb_zspmat_type, psb_dpk_, psb_z_base_sparse_mat
+      class(psb_zspmat_type), intent(inout) :: a
+      integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+      integer(psb_ipk_), intent(out)          :: info
+    end subroutine psb_z_merge_nd
+  end interface
 
   !
   ! CSCNV: switches to a different internal derived type.
diff --git a/base/serial/impl/psb_c_mat_impl.F90 b/base/serial/impl/psb_c_mat_impl.F90
index bbac0406..532cb9b8 100644
--- a/base/serial/impl/psb_c_mat_impl.F90
+++ b/base/serial/impl/psb_c_mat_impl.F90
@@ -1263,6 +1263,56 @@ subroutine psb_c_split_nd(a,n_rows,n_cols,info)
   
 end subroutine psb_c_split_nd
 
+subroutine psb_c_merge_nd(a,n_rows,n_cols,info)
+  use psb_error_mod
+  use psb_string_mod
+  use psb_c_mat_mod, psb_protect_name => psb_c_merge_nd
+  implicit none
+  class(psb_cspmat_type), intent(inout) :: a
+  integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+  integer(psb_ipk_), intent(out)          :: info
+!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
+!!$      character(len=*), optional, intent(in) :: type
+!!$      class(psb_c_base_sparse_mat), intent(in), optional :: mold
+  type(psb_c_coo_sparse_mat) :: acoo1,acoo2
+  integer(psb_ipk_) :: nz
+  logical, parameter :: use_ecsr=.true.
+  character(len=20)     :: name, ch_err
+  integer(psb_ipk_) :: err_act
+
+  info = psb_success_
+  name = 'psb_split'
+  call psb_erractionsave(err_act)
+
+  call a%ad%mv_to_coo(acoo1,info)
+  call acoo1%set_bld()
+  call acoo1%set_nrows(n_rows)
+  call acoo1%set_ncols(n_cols)
+  call a%and%mv_to_coo(acoo2,info)
+  nz=acoo2%get_nzeros()
+  call acoo1%csput(nz,acoo2%ia,acoo2%ja,acoo2%val,ione,n_rows,ione,n_cols,info)
+  if (allocated(a%a)) then
+    call a%a%free()
+    deallocate(a%a)
+  end if
+  allocate(a%a,mold=a%ad)
+  call a%a%mv_from_coo(acoo1,info)
+
+  if (psb_errstatus_fatal()) then    
+    info=psb_err_from_subroutine_
+    call psb_errpush(info,name,a_err='cscnv')
+    goto 9999
+  endif
+  
+  call psb_erractionrestore(err_act)
+  return
+  
+9999 call psb_error_handler(err_act)
+  
+  return
+  
+end subroutine psb_c_merge_nd
+
 subroutine psb_c_cscnv(a,b,info,type,mold,upd,dupl)
   use psb_error_mod
   use psb_string_mod
diff --git a/base/serial/impl/psb_d_mat_impl.F90 b/base/serial/impl/psb_d_mat_impl.F90
index 9af64b3f..e48654ce 100644
--- a/base/serial/impl/psb_d_mat_impl.F90
+++ b/base/serial/impl/psb_d_mat_impl.F90
@@ -1263,6 +1263,56 @@ subroutine psb_d_split_nd(a,n_rows,n_cols,info)
   
 end subroutine psb_d_split_nd
 
+subroutine psb_d_merge_nd(a,n_rows,n_cols,info)
+  use psb_error_mod
+  use psb_string_mod
+  use psb_d_mat_mod, psb_protect_name => psb_d_merge_nd
+  implicit none
+  class(psb_dspmat_type), intent(inout) :: a
+  integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+  integer(psb_ipk_), intent(out)          :: info
+!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
+!!$      character(len=*), optional, intent(in) :: type
+!!$      class(psb_d_base_sparse_mat), intent(in), optional :: mold
+  type(psb_d_coo_sparse_mat) :: acoo1,acoo2
+  integer(psb_ipk_) :: nz
+  logical, parameter :: use_ecsr=.true.
+  character(len=20)     :: name, ch_err
+  integer(psb_ipk_) :: err_act
+
+  info = psb_success_
+  name = 'psb_split'
+  call psb_erractionsave(err_act)
+
+  call a%ad%mv_to_coo(acoo1,info)
+  call acoo1%set_bld()
+  call acoo1%set_nrows(n_rows)
+  call acoo1%set_ncols(n_cols)
+  call a%and%mv_to_coo(acoo2,info)
+  nz=acoo2%get_nzeros()
+  call acoo1%csput(nz,acoo2%ia,acoo2%ja,acoo2%val,ione,n_rows,ione,n_cols,info)
+  if (allocated(a%a)) then
+    call a%a%free()
+    deallocate(a%a)
+  end if
+  allocate(a%a,mold=a%ad)
+  call a%a%mv_from_coo(acoo1,info)
+
+  if (psb_errstatus_fatal()) then    
+    info=psb_err_from_subroutine_
+    call psb_errpush(info,name,a_err='cscnv')
+    goto 9999
+  endif
+  
+  call psb_erractionrestore(err_act)
+  return
+  
+9999 call psb_error_handler(err_act)
+  
+  return
+  
+end subroutine psb_d_merge_nd
+
 subroutine psb_d_cscnv(a,b,info,type,mold,upd,dupl)
   use psb_error_mod
   use psb_string_mod
diff --git a/base/serial/impl/psb_s_mat_impl.F90 b/base/serial/impl/psb_s_mat_impl.F90
index c0370774..77ac81e6 100644
--- a/base/serial/impl/psb_s_mat_impl.F90
+++ b/base/serial/impl/psb_s_mat_impl.F90
@@ -1263,6 +1263,56 @@ subroutine psb_s_split_nd(a,n_rows,n_cols,info)
   
 end subroutine psb_s_split_nd
 
+subroutine psb_s_merge_nd(a,n_rows,n_cols,info)
+  use psb_error_mod
+  use psb_string_mod
+  use psb_s_mat_mod, psb_protect_name => psb_s_merge_nd
+  implicit none
+  class(psb_sspmat_type), intent(inout) :: a
+  integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+  integer(psb_ipk_), intent(out)          :: info
+!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
+!!$      character(len=*), optional, intent(in) :: type
+!!$      class(psb_s_base_sparse_mat), intent(in), optional :: mold
+  type(psb_s_coo_sparse_mat) :: acoo1,acoo2
+  integer(psb_ipk_) :: nz
+  logical, parameter :: use_ecsr=.true.
+  character(len=20)     :: name, ch_err
+  integer(psb_ipk_) :: err_act
+
+  info = psb_success_
+  name = 'psb_split'
+  call psb_erractionsave(err_act)
+
+  call a%ad%mv_to_coo(acoo1,info)
+  call acoo1%set_bld()
+  call acoo1%set_nrows(n_rows)
+  call acoo1%set_ncols(n_cols)
+  call a%and%mv_to_coo(acoo2,info)
+  nz=acoo2%get_nzeros()
+  call acoo1%csput(nz,acoo2%ia,acoo2%ja,acoo2%val,ione,n_rows,ione,n_cols,info)
+  if (allocated(a%a)) then
+    call a%a%free()
+    deallocate(a%a)
+  end if
+  allocate(a%a,mold=a%ad)
+  call a%a%mv_from_coo(acoo1,info)
+
+  if (psb_errstatus_fatal()) then    
+    info=psb_err_from_subroutine_
+    call psb_errpush(info,name,a_err='cscnv')
+    goto 9999
+  endif
+  
+  call psb_erractionrestore(err_act)
+  return
+  
+9999 call psb_error_handler(err_act)
+  
+  return
+  
+end subroutine psb_s_merge_nd
+
 subroutine psb_s_cscnv(a,b,info,type,mold,upd,dupl)
   use psb_error_mod
   use psb_string_mod
diff --git a/base/serial/impl/psb_z_mat_impl.F90 b/base/serial/impl/psb_z_mat_impl.F90
index 20815cb0..18d6c03d 100644
--- a/base/serial/impl/psb_z_mat_impl.F90
+++ b/base/serial/impl/psb_z_mat_impl.F90
@@ -1263,6 +1263,56 @@ subroutine psb_z_split_nd(a,n_rows,n_cols,info)
   
 end subroutine psb_z_split_nd
 
+subroutine psb_z_merge_nd(a,n_rows,n_cols,info)
+  use psb_error_mod
+  use psb_string_mod
+  use psb_z_mat_mod, psb_protect_name => psb_z_merge_nd
+  implicit none
+  class(psb_zspmat_type), intent(inout) :: a
+  integer(psb_ipk_), intent(in)           :: n_rows, n_cols
+  integer(psb_ipk_), intent(out)          :: info
+!!$      integer(psb_ipk_),optional, intent(in)           :: dupl
+!!$      character(len=*), optional, intent(in) :: type
+!!$      class(psb_z_base_sparse_mat), intent(in), optional :: mold
+  type(psb_z_coo_sparse_mat) :: acoo1,acoo2
+  integer(psb_ipk_) :: nz
+  logical, parameter :: use_ecsr=.true.
+  character(len=20)     :: name, ch_err
+  integer(psb_ipk_) :: err_act
+
+  info = psb_success_
+  name = 'psb_split'
+  call psb_erractionsave(err_act)
+
+  call a%ad%mv_to_coo(acoo1,info)
+  call acoo1%set_bld()
+  call acoo1%set_nrows(n_rows)
+  call acoo1%set_ncols(n_cols)
+  call a%and%mv_to_coo(acoo2,info)
+  nz=acoo2%get_nzeros()
+  call acoo1%csput(nz,acoo2%ia,acoo2%ja,acoo2%val,ione,n_rows,ione,n_cols,info)
+  if (allocated(a%a)) then
+    call a%a%free()
+    deallocate(a%a)
+  end if
+  allocate(a%a,mold=a%ad)
+  call a%a%mv_from_coo(acoo1,info)
+
+  if (psb_errstatus_fatal()) then    
+    info=psb_err_from_subroutine_
+    call psb_errpush(info,name,a_err='cscnv')
+    goto 9999
+  endif
+  
+  call psb_erractionrestore(err_act)
+  return
+  
+9999 call psb_error_handler(err_act)
+  
+  return
+  
+end subroutine psb_z_merge_nd
+
 subroutine psb_z_cscnv(a,b,info,type,mold,upd,dupl)
   use psb_error_mod
   use psb_string_mod