[FIXED] Python: numpy.sum returns wrong ouput (numpy version 1.21.3)

Issue

Here I have a 1D array:

>>> import numpy as np
>>> a = np.array([75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328,
                  75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328,
                  75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328,
                  75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328,
                  75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328,
                  75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328,
                  75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328,
                  75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328, 75491328])

And the sum of all elements in the array should be 75491328*8*8 = 4831444992. However, when I use np.sum, I get a different output.

>>> np.sum(a)
536477696

That's what happens on my Jupyter Notebook using the latest version of Numpy. But when I use Jupyter Notebook of Coursera using old version 1.18.4 of Numpy, everything is fine.

How can I fix this bug? Is it a bug or is it because of me? Please explain and help me fix this. Thanks in advanced.

Solution

The problem is caused by integer overflow, you should change the datatype of np.array to int64.

import numpy as np
np.array([Your values here], dtype=np.int64)

Answered By - Linux Geek