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Gamma Function Using Spouge's Method
08-22-2015, 08:35 AM
Post: #15
RE: Gamma Function Using Spouge's Methjod
(08-22-2015 02:09 AM)lcwright1964 Wrote:  
(08-21-2015 09:48 AM)Ángel Martin Wrote:  Indeed it was the formula with the coefficients published on Viktor's page.

Do you mean the seven q's and the formula rearranged for calculators?

If that is the case, you might want to know that the selection of the free parameter (Viktor calls it g, but it is a elsewhere) is from the original Lanczos paper and is quite arbitrary.

I can swear that I did up a Maple worksheet of this ages ago, that accepted these optimal parameters as input, solved Godfrey's matrix equations for the associated coefficients, doing it all to very generous arbitrary precision, and transformed them into the form recommended by Victor for calculator programming. But can I find the darn thing? Alas, no--that's a couple of hard drives ago.

If I do redo this I can compute and send you "improved" coefficients, in the event you ever tweak the code. It might not make much difference unless you can shorten your series by a term, but I sure would like to ponder the question.

I want to continue this discussion elsewhere in the forum as I have some broader newbie questions about the newest SandMath, Lib#4, and programming Nov-64 with this stuff (if possible).


Well, yes I tweak the code all the time (in fact just recently since Dieter found a bug in FLOOR) - but first of all, the reference I use doesn't have any free parameter that I can see. This is the link, and the coefficients are already shown in the more efficient way, I think:

I'm sure I'm missing something so will appreciate the enlightenment.

SandMath questions are always welcome, as a matter of fact I'm goinf to burn my own NoVRAM today with the updated version. It's been a while I did this, I mostly work on my CL units of course - much more comfortable and super fast.


"To live or die by your own sword one must first learn to wield it aptly."
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RE: Gamma Function Using Spouge's Methjod - Ángel Martin - 08-22-2015 08:35 AM

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