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Re: improving special functions in GSoC 2017
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From: |
Colin Macdonald |
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Subject: |
Re: improving special functions in GSoC 2017 |
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Date: |
Sat, 25 Jun 2016 23:08:28 -0700 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 |
On 25/06/16 02:54, Marco Caliari wrote:
"Special functions are expected by users to just work".
So I just found that our "besselj" gives NaNs for values like "1e10".
>> besselj(1, 1e9)
ans = -5.21042264155388e-06
>> besselj(1, 1e10)
ans = NaN + NaNi
https://savannah.gnu.org/bugs/index.php?48316
That's not some wild exotic function: its a common Bessel function!
Why are we not just calling some free-licensed library that nails these
things? For example, SciPy does:
>>> scipy.special.jn(1,1e9)
-5.2104226415538769e-06
>>> scipy.special.jn(1,1e10)
-7.676506113846571e-06