m/image/colormap.m improved compatibility with Matlab and input checking

[Massimo Lorenzin]

Bug report for Octave 2.0.13.90 configured for i386-redhat-linux-gnu.

Description:
Sorry for my poor english! :)
1) unlike Matlab 5, octave reports an error if colormap has a string as
input argument:
    e.g.
         >> colormap( 'gray' )

2)  >> colormap( map )
     colormap.m does'nt check if size( map,2 ) ~= 3 and if map values
aren't in [0,1] interval.

Fix: a replacement of colormap.m is attached.

Ciao ( bye ) !

--
Massimo Lorenzin

mailto:address@hidden















## 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.

## Set the current colormap.
##
## colormap (map) sets the current colormap to map.  map must be an n
## row by 3 column matrix. The columns contain red, green, and blue
## intensities respectively.  All entries must be between 0 and 1
## inclusive. The new colormap is returned.
##
## colormap ("default") restores the default colormap (a gray scale
## colormap with 64 entries). The default colormap is returned.
##
## colormap with no arguments returns the current colormap.

## Author: Tony Richardson <address@hidden>
## Created: July 1994
## Adapted-By: jwe

function cmap = colormap (map)

  global __current_color_map__ = gray ();

  if (nargin > 1)
    usage ("colormap (map)");
  endif

  if (nargin == 1)
    
    if (isstr (map))
      if (strcmp (map, "default"))
        map = gray ();
      else
        backup_eval_print_flag = default_eval_print_flag;
        default_eval_print_flag = 0;
        map = eval( map );
        default_eval_print_flag = backup_eval_print_flag;
      endif
    endif
    
    if (~isempty( map ))
      if (size(map,2) ~= 3)
        error( "Colormap must have 3 columns: [R,G,B]." );
      endif
      if ( min(min(map)) < 0 | max(max(map)) > 1 )
        error( "Colormap must have values in [0,1]." );
      endif
      ## Set the new color map
      __current_color_map__ = map;
    endif
  
  endif

  ## Return current color map.

  cmap = __current_color_map__;

endfunction