Added restart on breackdown.

src/methd/psb_dcg.f90

@@ -72,7 +72,7 @@ Subroutine psb_dcg(a,prec,b,x,eps,desc_a,info,&
   real(kind(1.d0))    ::rerr
   real(kind(1.d0))    ::alpha, beta, rho, rho_old, rni, xni, bni, ani,bn2,& 
        & sigma
-  integer         :: litmax, liter, listop, naux, m, mglob, it, itrac,&
+  integer         :: litmax, liter, listop, naux, m, mglob, it, itx, itrac,&
        & nprows,npcols,me,mecol, n_col, isvch, ich, icontxt, n_row,err_act, int_err(5)
   character          ::diagl, diagu
   logical, parameter :: exchange=.true., noexchange=.false.  
@@ -154,9 +154,12 @@ Subroutine psb_dcg(a,prec,b,x,eps,desc_a,info,&
   ich = 1 
   call blacs_set(icontxt,16,ich)
 
+  restart: do 
 !!$   
 !!$    r0 = b-Ax0
 !!$   
+    if (itx>= litmax) exit restart 
+    it = 0
     call psb_axpby(one,b,zero,r,desc_a,info)
     call psb_spmm(-one,a,x,one,r,desc_a,info,work=aux)
     if (info.ne.0) then 
@@ -179,7 +182,9 @@ Subroutine psb_dcg(a,prec,b,x,eps,desc_a,info,&
     end if
 
 
-  iteration:  do it = 1, itmax
+    iteration:  do 
+      it   = it + 1
+      itx = itx + 1
 
 !!$ 
 !!$  solve mz = r
@@ -230,7 +235,7 @@ Subroutine psb_dcg(a,prec,b,x,eps,desc_a,info,&
         xni = psb_amax(x,desc_a,info)
         rerr =  rni/(ani*xni+bni)
         If (itrac /= -1) Then 
-        If (me.Eq.0) Write(itrac,'(a,i4,5(2x,es10.4))') 'cg: ',it,rerr,rni,bni,&
+          If (me.Eq.0) Write(itrac,'(a,i4,5(2x,es10.4))') 'cg: ',itx,rerr,rni,bni,&
                &xni,ani
         Endif
 
@@ -239,21 +244,20 @@ Subroutine psb_dcg(a,prec,b,x,eps,desc_a,info,&
         rni = psb_nrm2(r,desc_a,info)
         rerr = rni/bn2
         If (itrac /= -1) Then 
-        If (me.Eq.0) Write(itrac,'(a,i4,3(2x,es10.4)))') 'cg: ',it,rerr,rni,bn2
+          If (me.Eq.0) Write(itrac,'(a,i4,3(2x,es10.4)))') 'cg: ',itx,rerr,rni,bn2
         Endif
       Endif
-
-    if (rerr<=eps) then 
-      exit iteration
-    end if
+      if (rerr<=eps) exit restart
+      if (itx>= litmax) exit restart 
     end do iteration
+  end do restart
 
   if (present(err)) err=rerr
-  if (present(iter)) iter = it
+  if (present(iter)) iter = itx
   if (rerr>eps) then
     write(0,*) 'CG Failed to converge to ',eps,&
          & ' in ',litmax,' iterations '
-    info=it
+    info=itx
   end if
 
   deallocate(aux)