Change handling of stopping criterion, refactor GMRES

linsolve/impl/psb_dcgstab.f90

@@ -156,13 +156,31 @@ Subroutine psb_dcgstab_vect(a,prec,b,x,eps,desc_a,info,itmax,iter,err,itrace,ist
 
   If (Present(istop)) Then 
     istop_ = istop 
-  Else
-    istop_ = 2
-  Endif
+  else
+    istop_ = psb_get_istop_default()
+  endif
+  if (.not.psb_is_valid_istop(istop_)) then
+    info=psb_err_invalid_istop_
+    err=info
+    call psb_errpush(info,name,i_err=(/istop_/))
+    goto 9999
+  end if
   !
-  !  ISTOP_ = 1:  Normwise backward error, infinity norm 
-  !  ISTOP_ = 2:  ||r||/||b||   norm 2 
+  !  istop_ = 1:  normwise backward error, infinity norm 
+  !  istop_ = 2:  ||r||/||b||   norm 2
   !
+  select case(istop_)
+  case(psb_istop_ani_,psb_istop_bn2_,&
+       & psb_istop_rn2_abs_, psb_istop_rrn2_)
+    ! nothing needed
+  case default
+    ! should never get here
+    info=psb_err_internal_error_
+    err=info
+    call psb_errpush(info,name,a_err="invalid istop_")
+    goto 9999
+  end select
+
   ! =  if (.not.same_type_as(x,b)) then 
   ! =    write(0,*) 'Warning: different dynamic types for X and B '
   ! =  end if