[AMPL 1854] Re: iterations

There is no builtin parameter that contains the number of iterations, unless the solver's interface has been written to create such a parameter.  And I don't know of any solver interfaces that does create such a parameter.

With most solvers, however, you can use the builtin parameter Initial.message to get a brief optimality message that contains the number of iterations.  (Initial is always the name of the current AMPL "problem" if you don't define a name.)  For example,

ampl: model nltransd.mod;

ampl: data nltrans.dat;

ampl: option solver minos;

ampl: solve;

MINOS 5.5: optimal solution found.

65 iterations, objective 427568.1225

Nonlin evals: obj = 139, grad = 138.

ampl: display Initial.message;

Initial.message = 'MINOS 5.5: optimal solution found.\

65 iterations, objective 427568.1225\

Nonlin evals: obj = 139, grad = 138.'

Initial.message is an AMPL string-valued item, and so you can apply AMPL's string functions to it to extract particular sub-strings, such as the number of iterations.  See section A.4.2 in the AMPL book for specifics.

Bob Fourer

4er@...