egs_exact: do not construct the matrix more often than necessary

It does not change unless the diff coeffs change.

1 files changed, 7 insertions, 3 deletions

diff --git a/mg2d.c b/mg2d.c
index 01c7624..1326a38 100644
--- a/mg2d.c
+++ b/mg2d.c
@@ -40,6 +40,7 @@ typedef struct MG2DLevel {
     unsigned int  depth;
 
     EGSContext *solver;
+    int egs_init_flags;
 
     GridTransferContext *transfer_restrict;
     GridTransferContext *transfer_prolong;
@@ -139,9 +140,10 @@ static int mg_solve_subgrid(MG2DContext *ctx, MG2DLevel *level)
                 level->solver->domain_size[1]);
 
         /* re-init the current-level solver (re-calc the residual) */
-        ret = mg2di_egs_init(level->solver);
+        ret = mg2di_egs_init(level->solver, level->egs_init_flags);
         if (ret < 0)
             return ret;
+        level->egs_init_flags |= EGS_INIT_FLAG_SAME_DIFF_COEFFS;
     }
 
     res_old = level->solver->residual_max;
@@ -198,7 +200,7 @@ static int mg_solve_subgrid(MG2DContext *ctx, MG2DLevel *level)
         /* re-init the current-level solver (re-calc the residual) */
         res_prev = level->solver->residual_max;
         start = gettime();
-        ret = mg2di_egs_init(level->solver);
+        ret = mg2di_egs_init(level->solver, 0);
         if (ret < 0)
             return ret;
         level->time_reinit += gettime() - start;
@@ -434,6 +436,8 @@ static int mg_levels_init(MG2DContext *ctx)
                 return ret;
         }
 
+        cur->egs_init_flags &= ~EGS_INIT_FLAG_SAME_DIFF_COEFFS;
+
         cur = cur->child;
     }
 
@@ -490,7 +494,7 @@ int mg2d_solve(MG2DContext *ctx)
     if (ret < 0)
         return ret;
 
-    ret = mg2di_egs_init(s_root);
+    ret = mg2di_egs_init(s_root, 0);
     if (ret < 0)
         return ret;