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Re: Fwd: qfunc/qfuncinv implementation in communications package
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From: |
Nir Krakauer |
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Subject: |
Re: Fwd: qfunc/qfuncinv implementation in communications package |
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Date: |
Fri, 25 Jan 2013 11:12:08 -0500 |
Unfortunately the NaN package replaces the built-in normcdf. When the
NaN package (version 2.5.5) is loaded in Octave 3.6.2, it gives the
wrong result:
> normcdf(-18)
ans = 0
Until this is fixed in the NaN package, erfc(18/sqrt(2))/2 is more
certain to return the right answer
Nir
On Fri, Jan 25, 2013 at 10:49 AM, Julien Bect <address@hidden> wrote:
> On 24/01/13 19:26, Richardson, Anthony wrote:
>> The function qfunc() in the communications package is currently
>> implemented as:
>> y = 1-normcdf(x);
>
> It should be normcdf(-x) instead. This is what I get under Octave 3.6.2 :
>
> octave:9> 1 - normcdf(7)
> ans = 1.27986510278788e-12
>
> octave:10> normcdf(-7)
> ans = 1.27981254388584e-12
>
> octave:11> 1 - normcdf(18)
> ans = 0
>
> octave:12> normcdf(-18)
> ans = 9.74094891893730e-73
>
> Best regards,
> Julien.