How to remove singularit​ies/discon​tinuities on 3D plots?

I want to plot some functions f(x,y) including singularities.

For example;

f(x,y)=tan(x-y)

• In Matlab, when I run the following code

syms x y;
func=@(x,y)  tan(x-y);
fsurf(@(x,y) func(x,y), [-4 2 -1 1])

I get

• In Mathematica, when I plot same function, I can remove the discontinouties using Exclusions -> "Singularities"

In MATLAB, how to remove vertical asymptote lines in the Matlab's figure like Mathematica?

-How to find the asymptote lines in Matlab? After finding the asymptote, maybe we make it invisible in the plot..

Answer 1

[John D'Errico]

There is no simple direct command to remove singularities. However, nothing stops you from setting the z axis limits.

syms x y;
func=@(x,y)  tan(x-y);
fsurf(@(x,y) func(x,y), [-4 2 -1 1])
zlim([-5,5])

[student_md]

All right, how to remove vertical asymptote lines in your figure?

[John D'Errico]

By the way, there was absolutely no need to use syms there. Defining the function as a function of the variables x and y is sufficient. That is, I needed do only as below.

The vertical lines will still be there, connecting each branch of the tangent function, from inf to -inf. Can you simply exclude them? Not that i can think of.

H = fsurf(@(x,y) tan(x-y), [-4 2 -1 1])

H = 
  FunctionSurface with properties:

     Function: @(x,y)tan(x-y)
       XRange: [-4 2]
       YRange: [-1 1]
    EdgeColor: [0 0 0]
    LineStyle: '-'
    FaceColor: 'interp'

  Show all properties

zlim([-5,5])

There is no assurance that you can always trivially do what another package does, down to the last bit. Could you do this? Well, I suppose, if you used meshgrid to create the surface, then replaced any elements larger than a max or smaller then a min with NaNs. But that would take a few more lines to write than the simple call to fsurf.

So without fsurf, where we cannot eliminate the unwanted vertical lines, we could have done this.

[x,y] = meshgrid(linspace(-4,2),linspace(-1,1));
func = @(x,y) tan(x-y);
z = func(x,y);
z((z > 5) | (z < -5)) = NaN;
surf(x,y,z)
xlabel x
ylabel y
zlabel z
grid on
box on
shading interp
colormap summer