[SciPy-user] conj and element-by-element multiplication

[David M. Cooke]

Ryan Krauss <ryanfedora at comcast.net> writes:

> No, I am running Linux.

Odd; I do too, and don't see this. glibc's pow doesn't have the same
problem as Window's does. x**2 is at most 50% slower, not 10x.

Which version of Numeric and python are you using, and which Linux
distribution? (Numeric's version you can get from Numeric.__version__)
Ideally, x**2 should run in the same time as x*x

You're using scipy's multiply, which is the same (I think) as the
multiply in Numeric 24.0b2, which are different from 23.8 and earlier
(which does a time-wasting postcheck of the array for infinite values).

> David M. Cooke wrote:
>
>     Ryan Krauss <ryanfedora at comcast.net> writes:
>
>
>
>         Thanks David, that seems like the right answer.  But to get the speed benefit
>         you mention, I need to use multiply(x.real,x.real) instead of x.real**2 - same
>         for imag.  There is about a factor of 10 time difference between the two.  So
>         my norm2 function now looks like this:
>
>
>
>     Are you on Windows? The pow() function there, well, sucks big time. On
>     other platforms the two are pretty close in speed.
>
>     I'm working on a better version of the power ufunc for Numeric, so
>     hopefully in a later version this will be fixed (or rather, worked
>     around).

-- 
|>|\/|<
/--------------------------------------------------------------------------\
|David M. Cooke                      http://arbutus.physics.mcmaster.ca/dmc/
|cookedm at physics.mcmaster.ca