[Ipopt] Error return from ma97_factor. Error flag = -7, Matrix found to be singular

[jmogali at andrew.cmu.edu]

Hi all,
         I am getting the following error in my code-: Error return from
ma97_factor. Error flag =  -7, Matrix found to be singular . Can
someone explain which matrix is becoming singular in my case.

FYI, in my program I repeatedly solve a problem with the same affine
constraints(across iterations) with little change to the objective
function (between iterations). It so happens that hessian and jacobian are
constant across iterations in my problem.


PS-: Note when I mean between and across iterations, I do not change it
while OptimizeTNLP() is being executed, rather after the solver finishes,
I just change the objective coefficients a bit and call OptimizeTNLP()
again using the same object that extends TNLP class C++.

Thanks ,
Jayanth