I can't graph multivariable function that contains cos function doens't work

I'm trying to graph f(x,y)=(e^x )* cos(y)

By using ulframalpha, I found that the graph should look like this.

>> x=[-4*pi:0.1:4*pi];

>> y=[-4*pi:0.1:4*pi];

>> [X,Y]=meshgrid(x,y);

>> Z=exp(X)*cos(Y);

>> surf(X,Y,Z)

My code look like this, and the result keep shows me this, flat plane.

I changed range for several times, but I don't think that range is not problem.

Can you see any problem in my code?

Any help would be aprreciated.

Answer 1

[Walter Roberson]

 Z=exp(X).*cos(Y);

Remember that the * operator is matrix multiplication (inner product). Multiplication of corresponding elements requires the .* operator.

[수정 이]

I appreciate your help. It was a such a trivial mistake but it made whole code doesn't work. Have a nice day :)