Re: Where is 'erf' defined and can we include 'erfcx'?

[Søren Hauberg]

tor, 04 03 2010 kl. 01:49 +0100, skrev Thomas Weber:
> On Wed, Mar 03, 2010 at 04:12:07PM -0800, Soren 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. 

Okay, I guess that means we are not using Netlib here. We'll just have
to come up with a solution in Octave-Forge then.

Thanks,
Soren