ex3: task 8

exercise3/wave_1d_parallel.c

@@ -50,6 +50,8 @@ real_t
 // Save the present time step in a numbered file under 'data/'.
 void domain_save(int_t step) {
   // BEGIN: T8
+  if (comm_rank != ROOT)
+    return;
   char filename[256];
   sprintf(filename, "data/%.5ld.dat", step);
   FILE *out = fopen(filename, "wb");