fix computation of checkpoint for checkpoint file name

bfps/DNS.py

@@ -775,7 +775,7 @@ class DNS(_code):
                     self.work_dir,
                     self.simname + '_checkpoint_0.h5')
     def get_checkpoint_fname(self, iteration = 0):
-        checkpoint = iteration // self.parameters['checkpoints_per_file']
+        checkpoint = (iteration // self.parameters['niter_out']) // self.parameters['checkpoints_per_file']
         return os.path.join(
                     self.work_dir,
                     self.simname + '_checkpoint_{0}.h5'.format(checkpoint))