On Thu, Nov 25, 2010 at 4:13 AM, Jean-Luc Menut wrote:
> Hello all,
>
> I have a little question about the speed of numpy vs IDL 7.0. I did a
> very simple little check by computing just a cosine in a loop. I was
> quite surprised to see an order of magnitude of difference between numpy
> and IDL,
On Thu, Nov 25, 2010 at 7:55 PM, Jean-Luc Menut wrote:
> Yes I know but IDL share this characteristics with numpy, and sometimes
> you cannot avoid loop. Anyway it was just a test to compare the speed of
> the cosine function in IDL and numpy.
No, you compared IDL looping and python looping. You
Thanks for your answers!
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Thanks for your answers!
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On 11/25/2010 5:55 AM, Jean-Luc Menut wrote:
> it was just a test to compare the speed of
> the cosine function in IDL and numpy
The point others are trying to make is that
you *instead* tested the speed of creation
of a certain object type. To test the *function*
speeds, feed both large arrays.
Le 25/11/2010 11:51, Ernest Adrogué a écrit :
> I'm not an expert either, but the basic idea you have to get is
> that "for" loops in Python are slow. Numpy is not going to change
> this. Instead, Numpy allows you to work with "vectors" and "arrays"
> so that you need not putting loops in your code
Jean-Luc Menut free.fr> writes:
>
> I have a little question about the speed of numpy vs IDL 7.0.
>
> Here the IDL result:
> % Compiled module: $MAIN$.
> 2.837
>
> The python code:
> from numpy import *
> from time import time
> time1 = time()
> for j in range(1):
> for i i
Hi,
25/11/10 @ 11:13 (+0100), thus spake Jean-Luc Menut:
> I suppose that some of the difference may come from the default data
> type of 64bits in numpy and 32 bits in IDL. Is there a way to change the
> numpy default data type (without recompiling) ?
This is probably not the issue.
> And I'
Le 25/11/2010 11:38, Sebastian Walter a écrit :
> using math.cos instead of numpy.cos should be much faster.
> I believe this is a known issue of numpy.
You're right, with math.cos, the code take 4.3s to run, not as fast as
IDL, but a lot better.
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using math.cos instead of numpy.cos should be much faster.
I believe this is a known issue of numpy.
On Thu, Nov 25, 2010 at 11:13 AM, Jean-Luc Menut wrote:
> Hello all,
>
> I have a little question about the speed of numpy vs IDL 7.0. I did a
> very simple little check by computing just a cosine
Hello all,
I have a little question about the speed of numpy vs IDL 7.0. I did a
very simple little check by computing just a cosine in a loop. I was
quite surprised to see an order of magnitude of difference between numpy
and IDL, I would have thought that for such a basic function, the speed
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