// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) INRIA
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution.  The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt

function []=fgrayplot(x,y,f,strf,rect,nax,void)
    //[]=fgrayplot(x,y,f)
    // Trace en niveau de gris une surface
    // z=f(x,y) d\'efinie par un external f ( ex macro [y]=f(x))
    // on calcule d'abord f sur la grille definie par x.y
    // x et y sont des vecteurs implicites donnant les
    // abscisses et les ordonn\'ees des points de la grille
    // le niveau de gris choisi sur chaque maillage depend de la valeur
    //    moyenne de z dans le maillage.
    // Exemple : taper fgrayplot() pour voir un exemple .
    //    deff('[z]=Surf(x,y)','z=x**2+y**2');
    //    fgrayplot(-1:0.1:1,-1:0.1:1,Surf);
    //!

    [lhs,rhs]=argn(0);

    if rhs <= 0 then   // demo
        deff("[z]=Surf(x,y)","z=cos(x).^2+sin(y).^2");
        fgrayplot(-%pi:0.1:%pi,-%pi:0.1:%pi, Surf);
        f = gcf();
        f.color_map = coolcolormap(100);
        return
    end


    if rhs<3,
        error(msprintf(gettext("%s: Wrong number of input argument(s): At least %d expected.\n"), "fgrayplot", 3));
    end


    opts=[]
    if exists("style","local")==1 then opts=[opts,"style=style"],end
    if exists("strf","local")==1 then opts=[opts,"strf=strf"],end
    if exists("rect","local")==1 then opts=[opts,"rect=rect"],end
    if exists("nax","local")==1 then opts=[opts,"nax=nax"],end
    if exists("frameflag","local")==1 then opts=[opts,"frameflag=frameflag"],end
    if exists("axesflag","local")==1 then opts=[opts,"axesflag=axesflag"],end

    if type(f)==11 then comp(f),end;
    execstr("grayplot(x,y,feval(x,y,f),"+strcat(opts,",")+")")
endfunction