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[Octave-bug-tracker] [bug #48307] sinc loses precision for large argumen
From: |
Colin Macdonald |
Subject: |
[Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments |
Date: |
Tue, 5 Jul 2016 04:24:20 +0000 (UTC) |
User-agent: |
Mozilla/5.0 (X11; Fedora; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0 |
Follow-up Comment #24, bug #48307 (project octave):
> symbolic IS using long double
Symbolic is using arbitrary precision via the mpmath library. I have compared
the results to Maple, I did so down below and they matched...
Here's something like what you want, although to me this just shows that two
independent arbitrary precision calculators give the same result.
Symbolic:
>> sin(pi*x) / (pi*x)
ans = (sym)
-3⋅√3
──────────
20000002⋅π
>> digits(200)
>> vpa(ans)
ans = (sym)
-0.000000082699326043336203093078665439078872301720741882921909627713940272260
518294338639792193025104173122963842414014598385696672944197610371640960743486
670650135932398542467726274361779425593210227572018156
Maple:
> x := 10000001/3;
x := 10000001/3
> A := sin(Pi*x) / (Pi*x);
1/2
3 3
A := - -----------
20000002 Pi
> Digits := 200;
Digits := 200
> evalf(A);
-0.826993260433362030930786654390788723017207418829219096277139402722605182\
94338639792193025104173122963842414014598385696672944197610371640960743\
-7
486670650135932398542467726274361779425593210227572018154 10
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- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, (continued)
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Colin Macdonald, 2016/07/04
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Dan Sebald, 2016/07/04
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Lachlan Andrew, 2016/07/04
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Marco Caliari, 2016/07/04
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Marco Caliari, 2016/07/04
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Dan Sebald, 2016/07/04
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Lachlan Andrew, 2016/07/04
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Dan Sebald, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Colin Macdonald, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Colin Macdonald, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments,
Colin Macdonald <=
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Lachlan Andrew, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Dan Sebald, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Dan Sebald, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Colin Macdonald, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Marco Caliari, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Dan Sebald, 2016/07/05
- [Octave-bug-tracker] [bug #48307] sinc loses precision for large arguments, Colin Macdonald, 2016/07/06