Major iteration limit reached

[Yanzhe Yang]

Hi,

I am learning AMPL to solve a nonlinear problem with SNOPT solver. I encountered a problem with "Major iteration limit reached". Do you have any advice on that?

The output is:

SNOPT 7.5-1.2 : Major iteration limit reached.

2439 iterations, objective 240.0187311

Nonlin evals: obj = 1919, grad = 1918, constrs = 1919, Jac = 1918.

Given the document https://ampl.com/products/solvers/snopt-options/ and the discussion http://ampl.996311.n3.nabble.com/AMPL-10583-SNOPT-options-major-iterations-limit-td11316.html, I should be able to set the major iteration limit like

option snopt_option 'major_iterations_limit=10000';

But I have tried with "major_iterations_limit", "major_iterations", "iterations". No matter what I changed, it will return the same error. 

My run file is:

model test.mod;

data test.dat;

option snopt_option 'wantsol=1 major_iterations_limit=10000 iterations';

option solver snopt;

solve;

Thank you!

Best,

Yanzhe

[AMPL Google Group]

You should write

option snopt_options 'major_iterations_limit=10000';

If you call it "snopt_option" (without the s) then SNOPT will not recognize it. You can tell when SNOPT has successfully read your options, because it will echo them back at the beginning of its run:

ampl: option snopt_options 'major_iterations_limit=10000';
ampl: solve;
SNOPT 7.5-1.2 : wantsol=1
major_iterations_limit=10000

--
Robert Fourer
am...@googlegroups.com

{#HS:1201843960-81113#}

[Yanzhe Yang]

Ah, I can't believe I made this mistake~ Thanks so much for the help!