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

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)

Answer 1

[Star Strider]

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)

[DIMITRIS GEORGIADIS]

Thank you. However, because this is part of an overall code I need to use the syms command. Is there an other way to implement it using syms?

[Star Strider]

Sure!

Try this:

syms x y
f(x,y) = sin(x)+cos(y);

figure(1)
fmesh(f, [0 5   1 6])
xlabel('X')
ylabel('Y')

[DIMITRIS GEORGIADIS]

Thank you very much!

[Star Strider]

As always, my pleasure!

[Karan Gill]

@Dimitris, or use fsurf instead of fmesh.

@Star Strider, actually it's only

>> f = @(x,y) sin(x)+cos(y);
>> fsurf(f)