A little problem with negative exponentiation

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Archiver
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A little problem with negative exponentiation

Post by Archiver »



Hello:

I have a little confusion, in the model that I'm developing there is a
constraint that has terms like this:

(Log10(R)*)*n, (Log10(S))**m

the problem is R and S are continuous variables between 1 & 0, and
with Log10 (R) or Log10(S), gives a negative number , and n,m are real
and positive numbers, hence the solver gives me the following error:

**** Exec Error at line 690: rPower: FUNC DOMAIN: x**y, x < 0

is there a way to include exponentitation of negative numbers??

thanks,
best regards

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Archiver
User
User
Posts: 7876
Joined: 7 years ago

Re: A little problem with negative exponentiation

Post by Archiver »



Daniel, the real power is not defined for a negative base (e.g.
http://www.cppreference.com/stdmath/pow.html). iI your n and m are
integers, you could use integer power:

GAMS Syntax: power(Log10(R),n) and power(Log10(S),m).

Michael Bussieck, GAMSWorld Coordinator

On Jul 24, 4:46 pm, Daniel wrote:
> > Hello:
> >
> > I have a little confusion, in the model that I'm developing there is a
> > constraint that has terms like this:
> >
> > (Log10(R)*)*n, (Log10(S))**m
> >
> > the problem is R and S are continuous variables between 1 & 0, and
> > with Log10 (R) or Log10(S), gives a negative number , and n,m are real
> > and positive numbers, hence the solver gives me the following error:
> >
> > **** Exec Error at line 690: rPower: FUNC DOMAIN: x**y, x >
> > is there a way to include exponentitation of negative numbers??
> >
> > thanks,
> > best regards
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