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Faster inverse gamma and factorial for the WP 34S
02-08-2015, 11:06 PM (This post was last modified: 02-09-2015 06:16 AM by BarryMead.)
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RE: Faster inverse gamma and factorial for the WP 34S
(02-08-2015 10:54 PM)rprosperi Wrote:  Thanks for explaining that viewpoint Barry, it helps. I think I asked my question the wrong way. It seems it came out sounding like "why bother doing this?", which was not my intent. I guess I meant to ask closer to "what application benefits from these functions having such precise capabilities?" I realize that this thread is more about building accurate and precise tools to be used by others for who knows what purpose, I'm just fishing for some of those purposes, if anyone here knows. Maybe not. Even if that's the case, it is rewarding to see such interesting collaboration and contributions to continually sharpen the tools.
To be honest I don't know what one would use a high accuracy inverse gamma function for. I have never needed one. I am sure that in some obscure corner of science people use this function and need it to be accurate, but I couldn't tell you off the top of my head how it would relate to a real-world application or need. As a nuclear physicist Walter probably uses more of the functions in the WP-34S for his everyday computations than just about anyone in this forum. Perhaps he or someone else in this forum can answer your question. Even though I don't personally know how/why the function is needed, I can appreciate the elegance of it's implementation like looking at fine painting or sculpture. I am relatively new to "Algorithm Design" myself. I did help fix the WP34S's complex hyperbolic tangent function, and Polar to Rectangular function, and helped Torsten Manz improve several algorithms in his HP-15C simulator including the Gamma function, and most of the complex trig, and hyperbolic trig functions here, but I am by no means an expert. I could not have written the algorithms that Bit and Dieter submitted. I know just enough to begin to appreciate some of the techniques used to keep the errors small, but not enough to optimize them for program size or speed. There is a real science and art to "Algorithm Design". I own several books on the subject and it gets deep pretty fast.
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RE: Faster inverse gamma and factorial for the WP 34S - BarryMead - 02-08-2015 11:06 PM

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