### Copyright (C) 1996 John W. Eaton
###
### This file is part of Octave.
###
### Octave is free software; you can redistribute it and/or modify it
### under the terms of the GNU General Public License as published by
### the Free Software Foundation; either version 2, or (at your option)
### any later version.
###
### Octave is distributed in the hope that it will be useful, but
### WITHOUT ANY WARRANTY; without even the implied warranty of
### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
### General Public License for more details.
###
### You should have received a copy of the GNU General Public License
### along with Octave; see the file COPYING.  If not, write to the Free
### Software Foundation, 59 Temple Place - Suite 330, Boston, MA
### 02111-1307, USA.

## usage: msg = strerror (name, err)
##
## Return the text of an error message for error number `err' from
## function "name".
##
## Messages correspond to the following subroutine versions:
##
##   npsol : 4.0
##   qpsol : 3.2

function msg = strerror (name, err)

  if (nargin != 2)
    usage ("strerror (name, err)");
  endif

  if (! isstr (name))
    error ("strerror: first argument must be a string");
  endif

  if (! is_scalar (err))
    error ("strerror: second argument must be a scalar");
  endif

  if (strcmp (name, "fsolve"))

    if (err == -2)
      msg = "input error\n";
    elseif (err == -1)
      msg = "error encountered in user-supplied function\n";
    elseif (err == 1)
      msg = "solution converged to requested tolerance\n";
    elseif (err == 4)
      msg = "iteration limit exceeded\n";
    elseif (err == 3)
      msg = "iteration is not making good progress\n";
    else
      error ("strerror: unrecognized error code for fsolve");
    endif

  elseif (strcmp (name, "npsol"))

    if (err == 0)
      msg = "optimal solution found\n";
    elseif (err == 1)
      msg = "weak local solution found\n";
    elseif (err == 2)
      msg = "no feasible point for linear constraints and bounds\n";
    elseif (err == 3)
      msg = "no feasible point found for nonlinear constraints\n";
    elseif (err == 4)
      msg = "iteration limit reached\n";
    elseif (err == 6)
      msg = "current point cannot be improved upon\n";
    elseif (err == 7)
      msg = "user-supplied derivatives appear to be incorrect\n";
    elseif (err == 9)
      msg = "internal error: invalid input parameter\n";
    else
      error ("strerror: unrecognized error code for npsol");
    endif

  elseif (strcmp (name, "qpsol"))

    if (err == 0)
      msg = "optimal solution found\n";
    elseif (err == 1)
      msg = "weak local solution found\n";
    elseif (err == 2)
      msg = "solution appears to be unbounded\n";
    elseif (err == 3)
      msg = "solution appears optimal, but optimality can't be verified\n";
    elseif (err == 4)
      msg = "iterates of the QP phase appear to be cycling\n";
    elseif (err == 5)
      msg = "iteration limit reached during QP phase\n";
    elseif (err == 6)
      msg = "no feasible point found during LP phase\n";
    elseif (err == 7)
      msg = "iterates of the LP phase appear to be cycling\n";
    elseif (err == 8)
      msg = "iteration limit reached during LP phase\n";
    elseif (err == 9)
      msg = "internal error: invalid input parameter\n";
    else
      error ("strerror: unrecognized error code for qpsol");
    endif

  else

    error ("strerror: unrecognized function name");

  endif

endfunction
