function implplot(funct,xyrange,fns)
%
% Implicit Plot of a function
%
% function implplot(funct,xyrange,fns)
%
% funct is an 'inline' function f(x,y)=0.
%
% xyrange = [xmin,xmax,ymin,ymax] range over which x and y is plotted.
% (Default(-5,5), (-5,5))
%
% fns is the number of grid points used to calculate the plot.
% (Default fns=500)
%
% Example: 
% To plot x^2+y^2=4 write function f as an 'inline' function of x and y.
%
% f=inline('x^2+y^2-4','x','y')
% implplot(f,[-3 3 -3 3])
%
%On the resulting graph, the standard x-axis (y-axis) corresponds to x (y).


if nargin == 1;
        xyrange=[-5,5,-5,5];
        fns=200;
end

if nargin == 2; 
        fns=200;
end

xm=linspace(xyrange(1),xyrange(2),fns);
ym=linspace(xyrange(3),xyrange(4),fns);
[x,y]=meshgrid(xm,ym);
fvector=vectorize(funct);
fvalues=feval(fvector,x,y); 
contour(x,y,fvalues,[0,0],'b-');