Re: Non-negative results when solving a set of equations

[Jaroslav Hajek]

On Thu, Jun 5, 2008 at 8:43 AM, Francesco Potorti` <address@hidden> wrote:
>>> I have a set of equations (Ax = b) that I can solve with  A\b.
>>> However, due to physical reasons, the result can not contain negative values
>>> (they should be zero in that case). I went through the manual and did a
>>> search, but found nothing that could help me.
>
> That depends on what you want.  If you want to "solve" the equations,
> there is nothing to do, because you hav a single solution, provided that
> A is non-singular.
>
> If you want simply to set negative values to zero, you do:
> x=A\b; x(x<0)=0;
>
>>If you are not satisfied with simply setting the negative components of
>>the solution to zero, look for function lsqnonneg.
>
> Interesting.  Is there a free implementation for Octave?
>

lsqnonneg is already part of Octave. If it is not in 3.0.1 (I'm not
sure now), it will be in 3.0.2.
Can't comment further, I haven't seen the code and I have never used it.

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-- 
RNDr. Jaroslav Hajek
computing expert
Aeronautical Research and Test Institute (VZLU)
Prague, Czech Republic
url: www.highegg.matfyz.cz