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Re: Where is 'erf' defined and can we include 'erfcx'?
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From: |
Thomas Weber |
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Subject: |
Re: Where is 'erf' defined and can we include 'erfcx'? |
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Date: |
Thu, 4 Mar 2010 01:49:32 +0100 |
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User-agent: |
Mutt/1.5.18 (2008-05-17) |
On Wed, Mar 03, 2010 at 04:12:07PM -0800, Søren Hauberg wrote:
> Hi All
>
> We had an inquiry on the Octave-Forge list regarding having a proper
> implementation of the 'erfcx' function. This functions computes
>
> exp(x^2)*erfc(x)
>
> in a numerically stable way. The poster mentioned that other people seem
> to use
>
> http://www.netlib.org/specfun/erf
>
> for evaluating this. I was wondering if we were already using the Netlib
> code for evaluating 'erf'? (I couldn't find the definition of 'erf' in
> the source code; where can I find this?) If we already use Netlib, then
> I guess the easiest solution would be to also include 'erfcx' in Octave.
> If not, well then we'll create something for Octave-Forge.
erf is already in libc for real arguments.
Thomas