diff --git a/samples/advanced/pdegen/amg_d_genpde_mod.F90 b/samples/advanced/pdegen/amg_d_genpde_mod.F90
index 604d4974..7bf4b128 100644
--- a/samples/advanced/pdegen/amg_d_genpde_mod.F90
+++ b/samples/advanced/pdegen/amg_d_genpde_mod.F90
@@ -412,9 +412,9 @@ contains
           ! compute gridpoint coordinates
           call idx2ijk(ix,iy,iz,glob_row,idim,idim,idim)
           ! x, y, z coordinates
-          x = (ix-1)*deltah
-          y = (iy-1)*deltah
-          z = (iz-1)*deltah
+          x = (ix)*deltah
+          y = (iy)*deltah
+          z = (iz)*deltah
           zt(k) = f_(x,y,z)
           ! internal point: build discretization
           !
@@ -875,8 +875,8 @@ contains
           ! compute gridpoint coordinates
           call idx2ijk(ix,iy,glob_row,idim,idim)
           ! x, y coordinates
-          x = (ix-1)*deltah
-          y = (iy-1)*deltah
+          x = (ix)*deltah
+          y = (iy)*deltah
 
           zt(k) = f_(x,y)
           ! internal point: build discretization
diff --git a/samples/advanced/pdegen/amg_s_genpde_mod.F90 b/samples/advanced/pdegen/amg_s_genpde_mod.F90
index c481fc07..bc99530d 100644
--- a/samples/advanced/pdegen/amg_s_genpde_mod.F90
+++ b/samples/advanced/pdegen/amg_s_genpde_mod.F90
@@ -412,9 +412,9 @@ contains
           ! compute gridpoint coordinates
           call idx2ijk(ix,iy,iz,glob_row,idim,idim,idim)
           ! x, y, z coordinates
-          x = (ix-1)*deltah
-          y = (iy-1)*deltah
-          z = (iz-1)*deltah
+          x = (ix)*deltah
+          y = (iy)*deltah
+          z = (iz)*deltah
           zt(k) = f_(x,y,z)
           ! internal point: build discretization
           !
@@ -875,8 +875,8 @@ contains
           ! compute gridpoint coordinates
           call idx2ijk(ix,iy,glob_row,idim,idim)
           ! x, y coordinates
-          x = (ix-1)*deltah
-          y = (iy-1)*deltah
+          x = (ix)*deltah
+          y = (iy)*deltah
 
           zt(k) = f_(x,y)
           ! internal point: build discretization
diff --git a/samples/simple/pdegen/amg_dpde_mod.f90 b/samples/simple/pdegen/amg_dpde_mod.f90
index 5bfe79aa..e6883248 100644
--- a/samples/simple/pdegen/amg_dpde_mod.f90
+++ b/samples/simple/pdegen/amg_dpde_mod.f90
@@ -144,7 +144,7 @@ contains
       f_ => d_null_func_3d
     end if
 
-    deltah   = 1.d0/(idim+1)
+    deltah   = 1.d0/(idim+2)
     sqdeltah = deltah*deltah
     deltah2  = 2.0_psb_dpk_* deltah
 
@@ -369,9 +369,9 @@ contains
         ! compute gridpoint coordinates
         call idx2ijk(ix,iy,iz,glob_row,idim,idim,idim)
         ! x, y, z coordinates
-        x = (ix-1)*deltah
-        y = (iy-1)*deltah
-        z = (iz-1)*deltah
+        x = (ix)*deltah
+        y = (iy)*deltah
+        z = (iz)*deltah
         zt(k) = f_(x,y,z)
         ! internal point: build discretization
         !   
diff --git a/samples/simple/pdegen/amg_spde_mod.f90 b/samples/simple/pdegen/amg_spde_mod.f90
index 78907603..d2d55447 100644
--- a/samples/simple/pdegen/amg_spde_mod.f90
+++ b/samples/simple/pdegen/amg_spde_mod.f90
@@ -144,7 +144,7 @@ contains
       f_ => s_null_func_3d
     end if
 
-    deltah   = 1.d0/(idim+1)
+    deltah   = 1.d0/(idim+2)
     sqdeltah = deltah*deltah
     deltah2  = 2.0_psb_spk_* deltah
 
@@ -369,9 +369,9 @@ contains
         ! compute gridpoint coordinates
         call idx2ijk(ix,iy,iz,glob_row,idim,idim,idim)
         ! x, y, z coordinates
-        x = (ix-1)*deltah
-        y = (iy-1)*deltah
-        z = (iz-1)*deltah
+        x = (ix)*deltah
+        y = (iy)*deltah
+        z = (iz)*deltah
         zt(k) = f_(x,y,z)
         ! internal point: build discretization
         !