Merge pull request #436 from strigi-form/fix435

MaxPool2D checks (#435)

nn.go

@@ -334,7 +334,6 @@ func MaxPool2D(x *Node, kernel tensor.Shape, pad, stride []int) (*Node, error) {
 	xShape := x.Shape()
 	h, w := xShape[2], xShape[3]
 	kh, kw := kernel[0], kernel[1]
-	ph, pw := pad[0], pad[1]
 
 	// check shape
 	if xShape.Dims() != 4 {
@@ -344,12 +343,36 @@ func MaxPool2D(x *Node, kernel tensor.Shape, pad, stride []int) (*Node, error) {
 		return nil, errors.Errorf("Expected kernel to have a shape of dimension 2")
 	}
 
-	if h-kh == 0 && ph == 0 {
+	// checks
+	for _, s := range stride {
+		if s <= 0 {
+			return nil, errors.Errorf("Cannot use strides of less than or equal 0: %v", stride)
+		}
+	}
+
+	for _, p := range pad {
+		if p < 0 {
+			return nil, errors.Errorf("Cannot use padding of less than 0: %v", pad)
+		}
+	}
+
+	padNorth := pad[0]
+	padWest := pad[1]
+	padSouth := pad[0]
+	padEast := pad[1]
+	if len(pad) == 4 {
+		padNorth = pad[0]
+		padSouth = pad[1]
+		padWest = pad[2]
+		padEast = pad[3]
+	}
+
+	if h-kh+padNorth+padSouth < 0 {
 		// error
 		return nil, errors.New("Impossible height/kernel/pad combination")
 	}
 
-	if w-kw == 0 && pw == 0 {
+	if w-kw+padWest+padEast < 0 {
 		// error
 		return nil, errors.New("Impossible width/kernel/pad combination")
 	}