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Besseli Function
From: |
John W. Eaton |
Subject: |
Besseli Function |
Date: |
Mon, 8 Sep 2003 11:33:19 -0500 |
On 8-Sep-2003, Jose Otavio Bueno <address@hidden> wrote:
| I'm having problems with the Besseli Functions in Octave. While with
| Mathlab it is possible to solve the besseli functions with values up to
| 700, with Octave the function returns a valid answer just for input
| values below 81:
Octave allows you to ask to have the result from besseli scaled by
exp(-abs(x)). So you can write
exp (abs (x)) * besseli (0, x, true);
(the last argument to besseli can be anything, its presence just means
"scale the result"). By doing this, Octave returns
octave:1> x = [1,10,81,82,700];
octave:2> exp(x).*besseli (0, x, true)
ans =
1.2661e+00 2.8157e+03 6.6864e+33 1.8064e+34 1.5296e+302
It might be useful if Octave detected the overflow (the internal
function zbesi provides that information) and then attempted to
perform the scaled calculation instead. Can someone please look at
providing a patch for that?
Also, the documentation for the scaling option could be better, so a
patch for that would also be appreciated.
Thanks,
jwe
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