Slice through a surface plot to create a contour plot

https://www.mathworks.com/matlabcentral/answers/504436-slice-of-a-surface-plot-created-by-2d-data?s_tid=prof_contriblnk

This is my previous question.

I have the same 3D surface plot, and now I need to create a 2D coutour plot at z = 0.

Is there a way to do that? Thanks.

Now i have something like this by putting

contour(xMat,yMat,delta_r2)

right after

surfl(xMat,yMat,delta_r2,'light')

but when this is just notmal "surf" instead of "surfl" it doesn't work and I need a 2D contour plot, not a slice in a 3D plot.

[Mohammad Sami]

I think if you have a function call to surf, you can just replace it with function call to contour and you will get your contour plot.

[Mai Sakuragi]

Hi, thank you for your comment. Unfortunately I am dealing with numerical values and there are no functions...

The 3D plot on the website (previous question) was build with numerical values.