Making some minor contributions to GSL

linas@austin.ibm.com linas@austin.ibm.com
Tue Jan 13 18:17:00 GMT 2004


Hi,

I have some code that might be appropriate for inclusion with GSL,
and was curious to gauge interest, and understand the hurdles 
involved.  

Polygamma functions, Abramowitz & Stegun chapter 6.4 -- these
are derivatives of the gamma (factorial) function.   The algo
I have is fairly straightforward ... and is accurate to about
1e-14 or so for "small" orders and arguments.  (The "multiplication
theorm" breaks down above order 30 or 40 or so, i.e. for arguments
greater than a 100 or 200 or so. I'm not sure why.)

I was wondering whether being accurate in this limited domain is 
adequate for inclusion of GSL, or whether the policy is to include 
only those algos that work well over the whole domain ... 
(and would thus require some additional, maybe hard work to get 
to there).

Determinant: I've got some code that computes determinants of 
a matrix.  It does it the "straightforward" way, i.e. in O(n factorial)
time, which means its painfully slow for n>=15.   Since GSL
doesn't currently have a matrix determinant routine of any kind, 
I thought this might be handy...

--linas



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