Relaxed the convergence and tolerance failure checks to allow differe…

…nces beyond first six meaningful digits

src/CG.cpp

@@ -96,8 +96,8 @@ int CG(const SparseMatrix & A, CGData & data, const Vector & b, Vector & x,
   normr0 = normr;
 
   // Start iterations
-
-  for (int k=1; k<=max_iter && normr/normr0 > tolerance; k++ ) {
+  // Convergence check has a "safety" factor of 1.0e-6
+  for (int k=1; k<=max_iter && normr/normr0 > tolerance * (1.0 + 1.0e-6); k++ ) {
     TICK();
     if (doPreconditioning)
       ComputeMG(A, r, z); // Apply preconditioner

src/main.cpp

@@ -223,6 +223,7 @@ int main(int argc, char * argv[]) {
     totalNiters_ref += niters;
   }
   if (rank == 0 && err_count) HPCG_fout << err_count << " error(s) in call(s) to reference CG." << endl;
+  double normr_ref = normr;
   double refTolerance = normr / normr0;
 
   // Call user-tunable set up function.
@@ -283,7 +284,7 @@ int main(int argc, char * argv[]) {
     double last_cummulative_time = opt_times[0];
     ierr = CG( A, data, b, x, optMaxIters, refTolerance, niters, normr, normr0, &opt_times[0], true);
     if (ierr) ++err_count; // count the number of errors in CG
-    if (normr / normr0 > refTolerance) ++tolerance_failures; // the number of failures to reduce residual
+    if (1e6 * (normr - normr_ref > normr0)) ++tolerance_failures; // the number of failures to reduce residual
 
     // pick the largest number of iterations to guarantee convergence
     if (niters > optNiters) optNiters = niters;