fix division per zero in profile mode.

theano/compile/profilemode.py

@@ -187,7 +187,11 @@ class ProfileMode(Mode):
             for f,t,a,nb_call in atimes[:n_apply_to_print]:
                 tot+=t
                 ftot=tot*100/local_time
-                print '   %4.1f%%  %5.1f%%  %5.3fs  %5.3fs %.2es  %i  %i %s' % (f, ftot, t, tot, t/nb_call,nb_call, a[0], str(a[1]))
+                if nb_call==0:
+                    time_per_call = float('nan')
+                else:
+                    time_per_call = t/nb_call
+                print '   %4.1f%%  %5.1f%%  %5.3fs  %5.3fs %.2es  %i  %i %s' % (f, ftot, t, tot, time_per_call,nb_call, a[0], str(a[1]))
             print '   ... (remaining %i Apply instances account for %.2f%%(%.2fs) of the runtime)'\
                     %(max(0, len(atimes)-n_apply_to_print),
                       sum(f for f, t, a, nb_call in atimes[n_apply_to_print:]),