# How do I get a surface graph of my function f(x,y)?

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DIMITRIS GEORGIADIS on 18 Nov 2017
Commented: Karan Gill on 20 Nov 2017
I have the following code. My function is f(x,y) = sin(x)+cos(y). I want to replace x, y with sets a and b, respectively. I ude the subs function, but Z is a 51x51 sym, instead of 51x51 double in order to be plotted. Where is my mistake?
syms x y
f = sin(x)+cos(y);
a = [0:0.1:5];
b = [1:0.1:6];
[X, Y] = meshgrid(a,b);
Z = subs(f,[x y], {X, Y});
surf(X,Y,Z)

Star Strider on 18 Nov 2017
Use an anonymous function, and don’t use the Symbolic Math Toolbox. You don’t need it for this problem.
f = @(x,y) sin(x)+cos(y);
a = [0:0.1:5];
b = [1:0.1:6];
[X, Y] = meshgrid(a,b);
Z = f(X,Y);
surf(X,Y,Z)
Karan Gill on 20 Nov 2017
@Dimitris, or use fsurf instead of fmesh.
@Star Strider, actually it's only
>> f = @(x,y) sin(x)+cos(y);
>> fsurf(f)

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