There is a "solver" you can invoke to get the numerical values of
derivatives at the current values of the variables. Details are given in
the file previously posted:
www.netlib.org/ampl/solvers/examples/README.gjh
Source code and makefiles for compiling this program are given in the same
directory. However, precompiled binaries for popular platforms can be found
in the subdirectories in www.netlib.org/ampl/student.
AMPL does not form analytical derivatives, so there is no way to get the
symbolic expressions for them.
Bob Fourer
4er@...
> -----Original Message-----
> From:
ampl@... [mailto:
ampl@...]
> On Behalf Of pioneer [
spencer.math@...]
> Sent: Monday, October 12, 2009 4:23 AM
> To: AMPL Modeling Language
> Subject: [AMPL 2876] Derivatives of variables
>
> Hi!
>
> Suppose I have say (just to illustrate the point),
> var x;
> var y;
> var g = x^2 + y^2;
>
> is it possible to get the derivative of g with respect to x or y from
> AMPL?
>
> Either as:
>
> (i) the numerical value of dg/dx, evaluated at the optimal solution
> or
> (ii) the analytical derivative, given as a symbolic expression
>
> Thanks
>
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