reimplemented the c code for the Module operator. It now always behave like python

theano/scalar/basic.py

@@ -843,42 +843,40 @@ class Mod(BinaryScalarOp):
     def impl(self, x, y):
         return x % y
     def c_code_cache_version(self):
-        return (3,)
+        return (4,)
 
     def c_code(self, node, name, (x, y), (z, ), sub):
         """
         We want the result to have the same sign as python, not the other implementaiton of mod.
         """
-        raise NotImplementedError()
         #raise NotImplementedError("Unlike Python, C's modulo returns negative modulo on negative dividend (to implement)")
         t = node.inputs[0].type.upcast(*[ i.type for i in node.inputs[1:]])
         if t in int_types or t in ['uint8','int8','uint16','int16','uint32','int32','uint64','int64']:
-            x_mod_y = "%(x)s %% %(y)s"%locals()
+            x_mod_y = "(%(x)s %% %(y)s)"%locals()
+            x_mod_ymm = "(-%(x)s %% -%(y)s)"%locals()
+            x_mod_ypm = "(%(x)s %% -%(y)s)"%locals()
+            x_mod_ymp = "(-%(x)s %% %(y)s)"%locals()
         elif t in float_types or t in ['float32','float64']:
             x_mod_y = "fmod(%(x)s,%(y)s)"%locals()
+            x_mod_ymm = "fmod(-%(x)s,-%(y)s)"%locals()
+            x_mod_ypm = "fmod(%(x)s,-%(y)s)"%locals()
+            x_mod_ymp = "fmod(-%(x)s,%(y)s)"%locals()
         else:
             raise NotImplementedError('type not supported', type)
         
         return """
-    if (%(x)s == 0 || %(y)s == 0) {
-        if (%(y)s == 0) %(z)s = %(x_mod_y)s;
-        %(z)s = 0;
-    }
-//was #if @neg@, I suspect @neg@ to be platform dependant.
-//should be true under X86, but could be false for other architecture!
-#if 1
-    else if ((%(x)s > 0) == (%(y)s > 0)) {
-        %(z)s = %(x_mod_y)s;
-    }
-    else { /* handled like Python does */
-        %(z)s = %(x_mod_y)s;
-        if (%(z)s) %(z)s += %(y)s;
-    }
-#else
-    else
-        %(z)s = %(x_mod_y)s;
-#endif
-"""%locals()
+if (%(x)s < 0){
+   if (%(y)s < 0){
+      %(z)s = -(%(x_mod_ymm)s);
+   }else{
+      %(z)s = - %(x_mod_ymp)s + (%(x_mod_ymp)s != 0 ? %(y)s : 0);
+   }
+}else if (%(y)s < 0){
+   %(z)s = (%(x_mod_ypm)s) + (%(x_mod_ypm)s != 0 ? %(y)s : 0);
+}else{
+   %(z)s = %(x_mod_y)s;
+}
+        """%locals()
     def grad(self, (x, y), (gz, )):
         return None, None
 mod = Mod(upcast_out, name = 'mod')