[racket] slow g^x=h mod p meet in the middle code

Cristian determined that Racket really was was much slower for the
program on Windows than on other platforms, and he also noticed that
RacketCGC was significantly faster.

That information pointed me to a simple inefficiency in the way Racket
allocated for GMP with the default collector. I've pushed a repair, and
Matthias's version of the program (which is a little faster than the
original) now runs about 4 times as fast on my machine (similar to the
Java version).

Fixing the bug was easy. The hard work was recognizing that something
was wrong and in what circumstances --- so thanks to everyone for that,
especially Cristian.

At Thu, 27 Feb 2014 19:10:06 -0500, Eric Dong wrote:
> On my computer the Java program takes 7 seconds. So you should be seeing a
> 3x slowdown with Racket.
> 
> You seem to see a 20x slowdown. This is very strange. How much RAM do you
> have? Racket performs very poorly when its memory is swapped out to disk.
> 
> To the rest of the list: is there any inefficiency with Racket on Windows
> that could cause this massive slowdown?
> 
> 
> On Thu, Feb 27, 2014 at 6:34 PM, Cristian Baboi 
> <cristian.baboi at gmail.com>wrote:
> 
> >
> >
> > On 28 februarie 2014 01:13:46 EET, Eric Dong <yd2dong at uwaterloo.ca> wrote:
> >
> >> Windows shouldn't be much slower though. What CPU model do you have?
> >> (2.0
> >> GHz can be fast or slow depending on your CPU model)
> >>
> >
> > AMD Athlon 3800+ X2
> >
> >
> > Also, can you post a Python program that runs much faster? Maybe it is
> >> only
> >> your computer which is slow, and it would be even slower running the
> >> Python
> >>
> >
> > I attached a Java program  I tested and it ran much faster. 13 s.
> >
> > I cannot test python because I don't have it installed and require some 
> libraries for big number arithmetic. I don't know python.
> >
> >
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