[Numpy-discussion] How fast are small arrays currently?
David M. Cooke
cookedm at physics.mcmaster.ca
Tue Jan 20 12:33:01 CST 2004
On Tue, Jan 20, 2004 at 02:42:03PM -0500, Edward C. Jones wrote:
> Has anyone recently benchmarked the speed of numarray vs. Numeric?
Just what I was doing :-)
Check out http://arbutus.mcmaster.ca/dmc/numpy/ for a graph comparing
the two.
Basically, I get on my machine (a 1.3 GHz Athlon running Linux), for an
array of size N (of Float), the time to do a+a is
Numeric: 3.7940e-6 + 2.2556e-8 * N seconds
numarray: 3.7062e-5 + 5.8497e-9 * N
For sin(a),
Numeric: 1.7824e-6 + 1.1341e-7 * N
numarray: 2.8994e-5 + 9.8985e-8 * N
So the slowness of numarray vs. Numeric for small arrays is because of
an overhead of 3.7e-5 s for numarray, as opposed to 3.8e-6 s for
Numeric. Otherwise, numarray is 4 times faster for large arrays
for addition (and multiplication, which I've also checked).
The crossover is at arrays of about 2000 elements.
If this overhead could be reduced by a factor of 3 or 4, I'd be much
happier with using numarray for small arrays. But for now, it's not
good enough.
--
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|David M. Cooke http://arbutus.physics.mcmaster.ca/dmc/
|cookedm at physics.mcmaster.ca
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