Python speed vs csharp

[Michele Simionato]

Alex Martelli <aleax at aleax.it> wrote in message news:<0MoXa.21930$cl3.850221 at news2.tin.it>...
> import math
> 
> def erfc(x):
>     exp = math.exp
> 
>     p  =  0.3275911
>     a1 =  0.254829592
>     a2 = -0.284496736
>     a3 =  1.421413741
>     a4 = -1.453152027
>     a5 =  1.061405429
> 
>     t = 1.0 / (1.0 + p*x)
>     erfcx = ( (a1 + (a2 + (a3 +
>                           (a4 + a5*t)*t)*t)*t)*t ) * exp(-x*x)
>     return erfcx
> 
> def main():
>     erg = 0.0
> 
>     for i in xrange(1000000):
>         erg += erfc(0.456)
> 
>     print "%f" % erg
> 
> if __name__ == '__main__':
>     main()
> 

Just for fun, I tested your scripts on my machine and actually my
results also substain the (heretic?) argument that Python (with psyco)
is *faster* than C for numeric computations:

                    Time        Relative to (optimized) C
                       
python+psyco       0.41s        0.59
c (-O option)      0.69s        1
c (normal)         0.80s        1.15
pure python        17.8s        26

This means that (in this computation) normal Python is 26 times
slower than optimized C; however Psyco gives a 43x speed-up and it 
ends up to be 70% faster!

It took my breath away.

Kudos to Armin Rigo and Psyco!

                          Michele


P.S. Red Hat Linux 7.2, 500 GHz PIII, time measured with 'time', 
Python 2.3 and Psyco 1.0, Alex Martelli scripts (with pow(x,2)-> x*x).