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Problem evaluating Zeta function
02-01-2016, 08:43 AM (This post was last modified: 02-01-2016 08:44 AM by retoa.)
Post: #1
Problem evaluating Zeta function
Hello all!

I was trying to evaluate the Riemann Zeta function.
Both in home and CAS it works when the imaginary part is an integer, I can evaluate Zeta(0.5+14i).
When the imaginary part is not an integer I become an answer containing the Eta function, I have found no way to have an approximate (real+imaginary) result. So for Zeta(0.5+14.1i) I can not find any usable evaluation.

How should I do it?

Thank you very much

Reto


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02-01-2016, 08:36 PM
Post: #2
RE: Problem evaluating Zeta function
Same behavior in xcad pad (with Eta function).
xcas on the PC (linux) evaluate it correctly and gives a complex number as a result.
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02-01-2016, 08:45 PM
Post: #3
RE: Problem evaluating Zeta function
Haven't looked at the source, but I'm guessing the numerical evaluation is tied in with one of the gpl license libraries and there is no alternate evaluation path... hence the ios one and also prime don't evaluate there.

TW

Although I work for HP, the views and opinions I post here are my own.
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02-02-2016, 07:25 AM
Post: #4
RE: Problem evaluating Zeta function
That's correct, PARI/GP is used on the PC... but there is giac code to handle Zeta computation as you can check with Xcas in your browser
http://www-fourier.ujf-grenoble.fr/~parisse/xcasen.html
It was probably not available when the last publicly available firmware was released.
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02-02-2016, 01:37 PM
Post: #5
RE: Problem evaluating Zeta function
Thank you Parisse,

I saw that xcas can compute it.

Does this mean that after the next firmware update the HP Prime will be able to compute Zeta function?
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02-02-2016, 03:18 PM
Post: #6
RE: Problem evaluating Zeta function
(02-02-2016 01:37 PM)retoa Wrote:  Does this mean that after the next firmware update the HP Prime will be able to compute Zeta function?

When/if there is another firmware update, then yes it would compute. I'd suspect that the ios one will right now, but I don't have a device handy to test.

TW

Although I work for HP, the views and opinions I post here are my own.
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02-02-2016, 06:32 PM
Post: #7
RE: Problem evaluating Zeta function
Yes, it works on the iOS prime app. I checked it against Wolfram Alpha. Both give the same result. Colm.
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