pypy on windows much slower than linux/mac when using complex number type?

[Christian Gollwitzer]

Am 23.09.16 um 21:50 schrieb Irmen de Jong:
> The problem boiled down to a performance issue in window's 32 bits implementation of the
> hypot() function   (which abs(z) uses when z is a complex number type).
> The 64 bits windows crt lib version is much faster (on par with what is to be expected
> from the linux or osx version), but  unfortunately there's no 64 bits pypy
> implementation for windows.
> Replacing abs(z) by sqrt(r*r+i*i) avoids the problem and is even faster still.

Interesting! Now beware that a "real" hypot function does approximately 
the following:

def myhypot(r, i):
     if abs(r)>abs(i):
       c = i/r
       return abs(r)*sqrt(1+c*c)
     else:
       if i==0:
         return 0.0
       else:
         c=r/i
         return abs(i)*sqrt(1+c*c)


it can well be, that the old 32bit MSVCRT does simply that, which 
requires some floating point ops, whereas the more modern 64bit lib uses 
hand-tuned SSE to perform the equivalent. Just for fun, you could try 
this hypot to see how it performs.


	Christian