ENH: used the rnorm from petsc as residual to be scaled by the normFactor

src/petsc/utils/PetscUtils.C

@@ -236,31 +236,21 @@ PetscErrorCode Foam::PetscUtils::foamKSPConverge
     KSPGetSolution(ksp, &psi);
     KSPGetRhs(ksp, &source);
 
-    // Precompute A dot psi
-    MatMult(A, psi, ctx->AdotPsi);
-
-    // Only compute normFactor on the first iteration
-    if (it == 0)
+    // compute the normFactor only at the first iteration    
     {
-        ctx->normFactor =
-            Foam::PetscUtils::normFactor
-            (
-                ctx->AdotPsi,
-                psi,
-                source,
-                ctx->ArowsSum
-            );
+        // precompute A dot psi
+        MatMult(A, psi, ctx->AdotPsi);
+        ctx->normFactor = Foam::PetscUtils::normFactor(A,
+                                                       ctx->AdotPsi,
+                                                       psi,
+                                                       source,
+                                                       ctx->ArowsSum,
+                                                       ctx->normFactorVec);
     }
 
-    PetscScalar residual =
-        calcResidual
-        (
-            source,
-            ctx->AdotPsi,
-            ctx->rA,
-            ctx->normFactor
-        );
-
+    // rescale the petsc norm (default l1) by the normFactor
+    PetscScalar residual = rnorm / ctx->normFactor;
+    
     if (it == 0)
     {
         solverPerf->initialResidual() = residual;