Merge pull request #241 from psnbaba/integrator_fix

added check particle array size

pysph/sph/integrator.py

@@ -86,15 +86,22 @@ def _get_explicit_dt_adapt(self):
                 'dt_adapt' in pa.properties for pa in a_eval.particle_arrays
             )
         if self._has_dt_adapt:
-            dt_min = 1e20
+            dt_min = np.inf
             for pa in a_eval.particle_arrays:
                 if 'dt_adapt' in pa.properties:
                     if pa.gpu is not None:
-                        from compyle.array import minimum
-                        min_val = minimum(pa.gpu.dt_adapt)
+                        if pa.gpu.get_number_of_particles() > 0:
+                            from compyle.array import minimum
+                            min_val = minimum(pa.gpu.dt_adapt)
+                        else:
+                            min_val = np.inf
                     else:
-                        min_val = np.min(pa.dt_adapt)
+                        if pa.get_number_of_particles() > 0:
+                            min_val = np.min(pa.dt_adapt)
+                        else:
+                            min_val = np.inf
                     dt_min = min(dt_min, min_val)
+
             if dt_min > 0.0:
                 return dt_min
             else:
@@ -161,7 +168,7 @@ def compute_time_step(self, dt, cfl):
         hmin = self.h_minimum
 
         # default time steps set to some large value
-        dt_cfl = dt_force = dt_viscous = 1e10
+        dt_cfl = dt_force = dt_viscous = np.inf
 
         # stable time step based on courant condition
         if dt_cfl_fac > 0:
@@ -180,7 +187,7 @@ def compute_time_step(self, dt, cfl):
 
         # return the computed time steps. If dt factors aren't
         # defined, the default dt is returned
-        if dt_min <= 0.0 or abs(dt_min - 1e10) < 1:
+        if dt_min <= 0.0 or np.isinf(dt_min):
             return None
         else:
             return cfl*dt_min