ASA <http://www.math.ufl.edu/~hager/papers/CG/Archive/>
===

-     0: convergence tolerance satisfied

-     4: number secant iterations exceed nsecant in cg

-     6: line search fails in initial interval in cg

-     8: line search fails during interval update in cg

-    13: search direction in cbb is not descent direction

-    15: cpu time limit exceeded


GENCAN <http://www.ime.usp.br/~egbirgin/tango/downloads.php>
======

-     0: Small continuous-projected-gradient norm

-     1: Maximum number of gencan iterations reached

-     3: Lack of progress in the objective function value

-     6: Unbounded objective function?

-     9: CPU time limit exceeded


fmincon
=======

-     1: first-order optimality less than OPTIONS.TolFun, and no
         negative/zero curvature detected in trust region model.

-     2: norm of the current step is less than OPTIONS.TolX.

-     3: relative function value changing by less than OPTIONS.TolFun.

-    66: Error using ==> mtimes
         Inner matrix dimensions must agree.

-    99: CPU time limit exceeded


LANCELOT <http://galahad.rl.ac.uk/galahad-www/download.html>
========

-     0: Successful termination.

-     3: The step taken during the current iteration is so small that no
         difference will be observed in the function values. This
         sometimes occurs when too much accuracy is required of the
         final gradient. If the projected gradient is small, the
         minimization has probably succeeded.

-    18: The current value of the merit function, inform%aug, is smaller
         than its smallest per- mitted value, control%min aug. Check
         the formulation to see if this seems reasonable.

-    99: CPU time limit exceeded.


L-BFGS-B <http://users.eecs.northwestern.edu/~nocedal/lbfgsb.html>
========

-     0: CONVERGENCE: NORM OF PROJECTED GRADIENT <= PGTOL            

-     3: CONVERGENCE: REL_REDUCTION_OF_F <= FACTR*EPSMCH             

-     5: WARNING: ABNORMAL TERMINATION IN LNSRCH
         Derivative >= 0, backtracking line search impossible.

-     1: WARNING: MAXIMUM NUMBER OF ITERATIONS REACHED

-     6: WARNING: UNBOUNDED OBJECTIVE FUNCTION

-     9: ERROR: CPU TIME LIMIT EXCEEDED


IPOPT <https://projects.coin-or.org/Ipopt#Download>
=====

-     0: Optimal Solution Found.

-    10: Error in step computation (regularization becomes too large?)!

-     3: Search Direction is becoming Too Small.

-     4: Solved To Acceptable Level.

-     9: Restoration Failed!

-    99: CPU Time Limit Exceeded!


SPG <http://www.ime.usp.br/~egbirgin/tango/downloads.php>
===

-     0: Solution was found.

-     1: CPU time limit exceeded.

-     3: Unbounded objective function?