Anomaly in python with matrix multiplication

Question

I have the following function:

def logistic(y):
    print((1-y).shape)
    print((y).shape)
    return y*(1-y)

The dimensions of y are 20 X 10. This function prints

20 X 10 20 X 10

And the function returns another matrix of dimension 20 X 10. In vector multiplication, the number of columns of the first argument must equal the number of rows of the 2nd argument. Even though this is not the case, how am I able to successfully execute this function?

Answer 1

"Because * does not do matrix multiplication. Rather, it does elementwise multiplication. Try numpy.dot or the @ operator if you have new enough python." Provided by User: jme