mg2d: ignore padding values in findmax()

1 files changed, 15 insertions, 12 deletions

diff --git a/mg2d.c b/mg2d.c
index 7f1ce4e..cc75a6e 100644
--- a/mg2d.c
+++ b/mg2d.c
@@ -66,14 +66,15 @@ struct MG2DInternal {
     double *boundaries_base[4];
 };
 
-static double findmax(double *arr, size_t len)
+static double findmax(double *arr, size_t size[2], ptrdiff_t stride)
 {
     double ret = 0.0;
-    for (size_t i = 0; i < len; i++) {
-        double val = fabs(*arr++);
-        if (val > ret)
-            ret = val;
-    }
+    for (size_t y = 0; y < size[1]; y++)
+        for (size_t x = 0; x < size[0]; x++) {
+            double val = fabs(arr[y * stride + x]);
+            if (val > ret)
+                ret = val;
+        }
     return ret;
 }
 
@@ -449,6 +450,8 @@ static int threadpool_init(MG2DContext *ctx)
 int mg2d_solve(MG2DContext *ctx)
 {
     MG2DInternal *priv = ctx->priv;
+    MG2DLevel    *root = priv->root;
+    EllRelaxContext *s_root = root->solver;
     int64_t time_start;
     double res_prev, res_cur;
     int ret;
@@ -465,18 +468,18 @@ int mg2d_solve(MG2DContext *ctx)
     if (ret < 0)
         return ret;
 
-    ret = mg2di_ell_relax_init(priv->root->solver);
+    ret = mg2di_ell_relax_init(s_root);
     if (ret < 0)
         return ret;
 
-    res_prev = findmax(priv->root->solver->residual,
-                       priv->root->solver->residual_stride * ctx->domain_size);
+    res_prev = findmax(s_root->residual, s_root->domain_size,
+                       s_root->residual_stride);
 
     for (int i = 0; i < ctx->maxiter; i++) {
-        mg_solve_subgrid(ctx, priv->root);
+        mg_solve_subgrid(ctx, root);
 
-        res_cur = findmax(priv->root->solver->residual,
-                          priv->root->solver->residual_stride * ctx->domain_size);
+        res_cur = findmax(s_root->residual, s_root->domain_size,
+                          s_root->residual_stride);
 
         if (res_cur < ctx->tol) {
             mg2di_log(&priv->logger, MG2D_LOG_INFO, "converged on iteration %d, residual %g\n",