 	__device__ float backward(float pos, float neg, int which) {
 		float f = neg - pos + margin;
 		if (which == 0) {
-			return -1 * (f > 0);
+			return -1. * (f > 0);
 		} else {
 			return f > 0;
 		}

	return 0;
}

static const struct luaL_Reg funcs[] = {
	{"ad", ad},
	{"census", census},

	{"writePFM", writePFM},
	{"grey2jet", grey2jet},
	{"spatial_argmin", spatial_argmin},

	{"version", version},
	{NULL, NULL}
};

