[Haskell-cafe] Re: Importing Data.Char speeds up ghc around 70%

Joost Behrends webmaster at h-labahn.de
Sat Dec 22 14:48:10 EST 2007

Daniel Fischer <daniel.is.fischer <at> web.de> writes:

> I can't reproduce it, both run in 130s here (SuSE 8.2, 1200MHz Duron).
> However, it's running over 30 minutes now trying to factorise 2^88+1 without 
> any sign of approaching success, which suggests your code has a bug (the 
> factorization is [257,229153,119782433,43872038849], so even a naive approach 
> shouldn't take much longer than a minute).
Yes, Daniel

the code is not completely correct. There is a known bug. Don't know the 
connection to your number, but it doesn't decompose 29*29*31*31 correctly
(gives [29,29,961] neither 59*59*61*61 (gives [59*59*3721]).

Difficult to find it, but that has nothing to do with the strange differences
of speed.

Cheers, Joost

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