[Numpy-discussion] Square All Elements Of A Matrix

[andrea_gavana at tin.it]

Hello NG,

    in one script, I generated a matrix "dx" which has a (200000, 10) shape.
Well, everything is working fine (matrix multiplication, sum, exponentiation
etc...), but I'm having problems in squaring all elements of this matrix.

Suppose I have:

import Numeric
import random

dx = Numeric.ones((200000,10), Numeric.Float0, savespace=1)
dx[:,:] = random.random()

td1 = dx*2.0   ---> This takes about 0.2 seconds
td2 = dx**2.0 ---> This takes about 6 seconds

Why this difference? And why it is so slow the exponentiation? I have tried
the same operation in Matlab and it was almost instantaneous. I don't want
to stick with Matlab, noting the great job the Numeric developers have done.

Is there something that I am missing?

Sorry if it is a basic question.

Andrea.