[Ipopt] TOO FEW DOF error

[Stefan Vigerske]

Hi,

I don't see how the number of constraints would double when enabling the 
derivative test. There must be more changes than the setting of the 
derivative_test option. It seems that somehow the number of constraints 
doubled, which will then look to Ipopt as if your problem is 
overdetermined, that is, there are more equations than variables. This 
results in the TOO_FEW_DOF exception.

Stefan

On 6/13/18 7:04 AM, Hisham Abdulla wrote:
> Hello,
> 
> When I run Ipopt with derivative_test, I get the following outputs.
> 
> *      Number of nonzeros in equality constraint Jacobian...:      640*
> 
> 
> 
> 
> *      Exception of type: TOO_FEW_DOF in file "IpIpoptApplication.cpp" at
> line 894:      Exception message: status != TOO_FEW_DEGREES_OF_FREEDOM
> evaluated false: Too few degrees of freedom (rethrown)!      EXIT: Problem
> has too few degrees of freedom.*
> 
> When I run my problem without derivative test,  the following are the
> ouputs.
> 
>       * Number of nonzeros in equality constraint Jacobian...:      320*
> 
> *      EXIT: Converged to a point of local infeasibility. Problem may be
> infeasible.*
> 
> 
> What does this indicate?  My problem surely is feasible. Are my constraints
> wrong?  Why the non-zeros in constraints Jacobian are different in two
> outputs?
> 
> Thank you
> 
> Hisham
> 
> 
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