[Ipopt] Same input, different output if executed in a loop (c++)

[Roberto Verdelli]

Hi,

I did some testing and I noticed that it also happens with the tutorial
problem written on the ipopt website.

My code looks like this:

int main(int argv, char* argc[]){

    for(int i = 0; i < 15; i++)
        loop();

}

int loop(){

// Create a new instance of your nlp
//  (use a SmartPtr, not raw)
SmartPtr<TNLP> mynlp = new hs071_nlp(/*a,b,c,d*/);

// Create a new instance of IpoptApplication
...


The function called 'loop' contains the tutorial ipopt problem.
If I lower the tolerance to 1e-3 (which shouldn't be a problem because if
the algorithm is deterministic two consecutive runs should look the same,
independently from the tolerance) I get this results:
iterations
1.Objective...............:  1.7014117428683792e-007
1.7014117428683793e+001
2.Objective...............:  1.7014117428684237e-007
1.7014117428684237e+001
3.Objective...............:  1.7014117428684237e-007
1.7014117428684237e+001
4.Objective...............:  1.7014117428684237e-007
1.7014117428684237e+001


Why the first iteration is different?


Kind regards,
Roberto.
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