In [1]:

    

class MulLayer:
    def __init__(self):
        self.x = None
        self.y = None
        
    def forward(self, x, y):
        self.x = x
        self.y = y
        out = x * y
        return out
    
    def backward(self, dout):
        dx = dout * self.y
        dy = dout * self.x
        return dx, dy


    

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In [2]:

    

apple = 100
apple_num = 2
tax = 1.1

# layer
mul_apple_layer = MulLayer()
mul_tax_layer = MulLayer()

# Forward
apple_price = mul_apple_layer.forward(apple, apple_num)
price = mul_tax_layer.forward(apple_price, tax)

print(price)


    

    




220.00000000000003

In [3]:

    

# Backward
dprice = 1
dapple_price, dtax = mul_tax_layer.backward(dprice)
dapple, dapple_num = mul_apple_layer.backward(dapple_price)

print(dapple, dapple_num, dtax)


    

    




2.2 110.00000000000001 200

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