--- a/scripts/optimization/glpk.m
+++ b/scripts/optimization/glpk.m
@@ -19,19 +19,28 @@
 
 ## GLPK - An Octave Interface for the GNU GLPK library
 ##
-## This routine calls the glpk library to solve an LP/MIP problem. A typical
-## LP problem has following structure:
+## This routine calls the glpk library to solve an LP/MIP problem.  By
+## default, glpk solves the following standard LP:
+##
+##   min C'*x
+##
+## subject to
+##
+##   A*x  = b
+##     x >= 0
 ##
-##           [min|max] C'x
-##            s.t.
-##                 Ax ["="|"<="|">="] b
-##                 {x <= UB}
-##                 {x >= LB}
+## but may also solve problems of the form
+##
+##   [min|max] C'x
+##
+## subject to
+##
+##   Ax ["="|"<="|">="] b
+##   {x <= UB}
+##   {x >= LB}
 ##
 ## The calling syntax is:
-## [XOPT,FOPT,STATUS,EXTRA]=glpk(SENSE,C,...
-##                               A,B,CTYPE,LB,UB,...
-##                               VARTYPE,PARAM,LPSOLVER,SAVE)
+## [XOPT,FOPT,STATUS,EXTRA]=glpk(C,A,B,LB,UB,CTYPE,VARTYPE,SENSE,PARAM)
 ##
 ## For a quick reference to the syntax just type glpk at command prompt.
 ##
@@ -40,11 +49,6 @@
 ##
 ## --- INPUTS ---
 ##
-## SENSE:     indicates whether the problem is a minimization
-##            or maximization problem.
-##            SENSE = 1 minimize
-##            SENSE = -1 maximize.
-##
 ## C:         A column array containing the objective function
 ##            coefficients.
 ##
@@ -53,6 +57,12 @@
 ## B:         A column array containing the right-hand side value for
 ##            each constraint in the constraint matrix.
 ##
+## LB:        An array of at least length numcols containing the lower
+##            bound on each of the variables.
+##
+## UB:        An array of at least length numcols containing the upper
+##            bound on each of the variables.
+##
 ## CTYPE:     A column array containing the sense of each constraint
 ##            in the constraint matrix.
 ##            CTYPE(i) = 'F'  Free (unbounded) variable
@@ -62,30 +72,20 @@
 ##            CTYPE(i) = 'D'  Double-bounded variable
 ##            (This is case sensitive).
 ##
-## LB:        An array of at least length numcols containing the lower
-##            bound on each of the variables.
-##
-## UB:        An array of at least length numcols containing the upper
-##            bound on each of the variables.
-##
 ## VARTYPE:   A column array containing the types of the variables.
 ##            VARTYPE(i) = 'C' continuous variable
 ##            VARTYPE(i) = 'I' Integer variable
 ##            (This is case sensitive).
 ##
+## SENSE:     indicates whether the problem is a minimization
+##            or maximization problem.
+##            SENSE = 1 minimize
+##            SENSE = -1 maximize.
+##
 ## PARAM:     A structure containing some parameters used to define
 ##            the behavior of solver. For more details type
 ##            HELP GLPKPARAMS.
 ##
-## LPSOLVER:  Selects which solver using to solve LP problems.
-##            LPSOLVER=1  Revised Simplex Method
-##            LPSOLVER=2  Interior Point Method
-##            If the problem is a MIP problem this flag will be ignored.
-##
-## SAVE:      Saves a copy of the problem if SAVE<>0.
-##            The file name can not be specified and defaults to "outpb.lp".
-##            The output file is CPLEX LP format.
-##
 ## --- OUTPUTS ---
 ##
 ## XOPT:      The optimizer.
@@ -145,11 +145,11 @@
 ## Author: Nicolo' Giorgetti <giorgetti@dii.unisi.it>
 ## Adapted-by: jwe
 
-function [xopt, fmin, status, extra] = glpk (sense, c, a, b, ctype, lb, ub, vartype, param, lpsolver, savepb)
+function [xopt, fmin, status, extra] = glpk (c, a, b, lb, ub, ctype, vartype, sense, param)
 
   ## If there is no input output the version and syntax
-  if (nargin < 4 || nargin > 11)
-    usage ("[xopt, fopt, status, extra] = glpk (sense, c, a, b, ctype, lb, ub, vartype, param, lpsolver, savepb");
+  if (nargin < 3 || nargin > 9)
+    usage ("[xopt, fopt, status, extra] = glpk (c, a, b, lb, ub, ctype, vartype, sense, param)");
     return;
   endif
 
@@ -161,7 +161,7 @@
   ## Force column vector.
   c = c(:);
 
-  ## 3) Matrix constraint
+  ## 2) Matrix constraint
 
   if (isempty (a))
     error ("A cannot be an empty matrix");
@@ -173,7 +173,7 @@
     return;
   endif
 
-  ## 4) RHS
+  ## 3) RHS
 
   if (isempty (b))
     error ("B cannot be an empty vector");
@@ -184,39 +184,22 @@
     return;
   endif
 
-  ## 5) Sense of each constraint
+  ## 4) Vector with the lower bound of each variable
 
-  if (nargin > 4)
-    if (isempty (ctype))
-      ctype = repmat ("U", nc, 1);
-    elseif (! ischar (ctype) || all (size (ctype) > 1) || length (ctype) != nc)
-      error ("CTYPE must be a char valued %d by 1 column vector", nc);
-      return;
-    elseif (! all (ctype == "F" | ctype == "U" | ctype == "S"
-		   | ctype == "L" | ctype == "D"))
-      error ("CTYPE must contain only F, U, S, L, or D");
-      return;
-    endif
-  else
-    ctype = repmat ("U", nc, 1);
-  end
-
-  ## 6) Vector with the lower bound of each variable
-
-  if (nargin > 5)
+  if (nargin > 3)
     if (isempty (lb))
-      lb = repmat (-Inf, nx, 1);
+      lb = zeros (0, nx, 1);
     elseif (! isreal (lb) || all (size (lb) > 1) || length (lb) != nx)
       error ("LB must be a real valued %d by 1 column vector", nx);
       return;
     endif
   else
-    lb = repmat (-Inf, nx, 1);
+    lb = zeros (nx, 1);
   end
 
-  ## 7) Vector with the upper bound of each variable
+  ## 5) Vector with the upper bound of each variable
 
-  if (nargin > 6)
+  if (nargin > 4)
     if (isempty (ub))
       ub = repmat (Inf, nx, 1);
     elseif (! isreal (ub) || all (size (ub) > 1) || length (ub) != nx)
@@ -227,9 +210,26 @@
     ub = repmat (Inf, nx, 1);
   end
 
-  ## 8) Vector with the type of variables
+  ## 6) Sense of each constraint
 
-  if (nargin > 7)
+  if (nargin > 5)
+    if (isempty (ctype))
+      ctype = repmat ("S", nc, 1);
+    elseif (! ischar (ctype) || all (size (ctype) > 1) || length (ctype) != nc)
+      error ("CTYPE must be a char valued %d by 1 column vector", nc);
+      return;
+    elseif (! all (ctype == "F" | ctype == "U" | ctype == "S"
+		   | ctype == "L" | ctype == "D"))
+      error ("CTYPE must contain only F, U, S, L, or D");
+      return;
+    endif
+  else
+    ctype = repmat ("S", nc, 1);
+  end
+
+  ## 7) Vector with the type of variables
+
+  if (nargin > 6)
     if isempty (vartype)
       vartype = repmat ("C", nx, 1);
     elseif (! ischar (vartype) || all (size (vartype) > 1)
@@ -245,7 +245,7 @@
     vartype = repmat ("C", nx, 1);
   endif
 
-  ## 9) Parameters vector
+  ## 8) Parameters vector
 
   if (nargin > 8)
     if (! isstruct (param))
@@ -256,29 +256,7 @@
     param = struct ();
   endif
 
-  ## 10) Select solver method: simplex or interior point
-
-  if (nargin > 9)
-    if (! (isreal (lpsolver) && isscalar (lpsolver)))
-      error ("LPSOLVER must be a real scalar value");
-      return;
-    endif
-  else
-    lpsolver = 1;
-  endif
-
-  ## 11) Save the problem
-
-  if (nargin > 10)
-    if (! (isreal (savepb) && isscalar (lpsolver)))
-      error ("LPSOLVER must be a real scalar value");
-      return;
-    endif
-  else
-    savepb = 0;
-  end
-
   [xopt, fmin, status, extra] = ...
-    __glpk__ (sense, c, a, b, ctype, lb, ub, vartype, param, lpsolver, savepb);
+    __glpk__ (c, a, b, lb, ub, ctype, vartype, sense, param);
 
 endfunction