[Ipopt] Restoration phase is called at point that is almost feasible, with constraint violation 4.202374e-007

[Sam Hall]

Dear the Ipopt team and Everyone,

I am doing a research on finite element. I am using IPOPT to optimize a problem.
I have provide all the Jacobian and Hessian Matrix, and I have used the derivative checker, no problem have be found.
But it displays "Restoration phase is called at point that is almost feasible,   with constraint violation 4.202374e-007" 
and "EXIT: Restoration Failed!" at the end of execution.

Sereval question i want to ask.
1. What is the meaning of "constraint violation 4.202374e-007" ? 
2. Do the result value come from this execution have be yet optimized? The problem is exited before the optimization or after the optimization ?
3. How can i improve this situation?

Thank you so much for your kind attention.

Best Regards,
Sam



NOTE: You are using Ipopt by default with the MUMPS linear solver.
      Other linear solvers might be more efficient (see Ipopt documentation).


This is Ipopt version 3.8.1, running with linear solver mumps.

Number of nonzeros in equality constraint Jacobian...:     1620
Number of nonzeros in inequality constraint Jacobian.:        0
Number of nonzeros in Lagrangian Hessian..............:     3459

Total number of variables.............................:      561
                     variables with only lower bounds:        0
                variables with lower and upper bounds:        0
                     variables with only upper bounds:        0
Total number of equality constraints.................:      135
Total number of inequality constraints...............:        0
        inequality constraints with only lower bounds:        0
   inequality constraints with lower and upper bounds:        0
        inequality constraints with only upper bounds:        0

iter    objective    inf_pr   inf_du lg(mu)  ||d||  lg(rg) alpha_du alpha_pr  ls
   0 0.0000000e+000 8.44e-003 0.00e+000  -1.0 0..00e+000    -  0.00e+000 0.00e+000   0
   1 3.5333238e+001 2.36e-003 1.22e+000  -3.8 1.26e+000    -  1.00e+000 1.00e+000h  1
   2 8.4242129e+001 5..54e-004 1.41e+001  -3.8 1.01e+000    -  1.00e+000 1.00e+000h  1
   3 1.1840200e+002 1.40e-004 4.17e+002  -3.8 5.48e-001    -  1.00e+000 1.00e+000h  1
   4 1.3770467e+002 3.59e-005 7.96e+001  -3.8 2.61e-001   2.0 1.00e+000 1.00e+000h  1
   5 1.4777208e+002 8.35e-006 2.77e+002  -3.8 4.88e-001    -  1.00e+000 1.00e+000h  1
   6 1.5287327e+002 2.07e-006 9.95e+001  -3.8 9.90e-002   1.5 1.00e+000 1.00e+000h  1
   7 1.5523371e+002 5.16e-007 3..56e+003  -3.8 4.30e-001    -  1.00e+000 1.00e+000h  1
   8 1.5656030e+002 1.29e-007 2.97e+003  -3.8 3.17e-002   1.9 1.00e+000 1.00e+000h  1
   9 1.5724789e+002 3.22e-008 7.36e+003  -3.8 4.86e-002   1.5 1.00e+000 1.00e+000h  1
iter    objective    inf_pr   inf_du lg(mu)  ||d||  lg(rg) alpha_du alpha_pr  ls
  10 1.5756944e+002 8.06e-009 2.81e+003  -3.8 1.50e-002   1..9 1.00e+000 1.00e+000h  1
  11 1.5756944e+002 8.06e-009 2.81e+003  -5.0 5.67e-007   9.7 1.00e+000 1.53e-005h 17
Restoration phase is called at point that is almost feasible,
  with constraint violation 4.202374e-007. Abort.

Number of Iterations....: 11

                                   (scaled)                 (unscaled)
Objective...............:  1.5756944002066021e+002   1.5756944002066021e+002
Dual infeasibility......:  2..8081119856712808e+003   2.8081119856712808e+003
Constraint violation....:  8.0629088961003959e-009   8.0629088961003959e-009
Complementarity..........:  0.0000000000000000e+000   0.0000000000000000e+000
Overall NLP error.......:  2.8408766197454791e-004   2.8081119856712808e+003


Number of objective function evaluations             = 52
Number of objective gradient evaluations             = 13
Number of equality constraint evaluations            = 52
Number of inequality constraint evaluations          = 0
Number of equality constraint Jacobian evaluations   = 13
Number of inequality constraint Jacobian evaluations = 0
Number of Lagrangian Hessian evaluations             = 12
Total CPU secs in IPOPT (w/o function evaluations)   =      0.280
Total CPU secs in NLP function evaluations           =      0.110

EXIT: Restoration Failed!