OK, if it's not reproducible in a standalone script, I'll close this as it's expected behaviour.

Correcting the typo in your script (__name__ == "__main__"), I ran it and it worked as expected on my system:

>type multi.py
import multiprocessing
import numpy
def f(x):
    return x*x

if __name__ == "__main__":
    p= multiprocessing.Pool(5)
    print(p.map(numpy.sqrt,[1,2,3,4]))
    print(p.map(f,[1,2,3,4]))
PS 15:05 {00:00.089} C:\Work\Scratch
>py .\multi.py
[1.0, 1.4142135623730951, 1.7320508075688772, 2.0]
[1, 4, 9, 16]

I'm not sure why you weren't getting output, but it doesn't look like a Python issue.