How to retrieve z value from surf plot given x and y?

I got a surface useing:

s= surf(X, Y, Z)

Since the X, Y, and Z are discrete, I want to get the consecutive value of Z. For example, the origin data X and Y are all integers, and I don't the relationship between XY and Z, I want to get the z value where X = 1.87 and Y = 2.9. Is it possible? What should I do?

Answer 1

[Cedric Wannaz]

Interpolate with INTERP2 : https://www.mathworks.com/help/matlab/ref/interp2.html

where Xq and Yq are defined using the values given in your question.

[Kyle Gao]

Thank you so much for your help! But I still need the query grid with a certain spacing value by using interp2. My problem is that I can't have the spacing value (or the grid), it needs to give me the Z value for a random X and Y. Any ideas?

[Cedric Wannaz]

Unless I misunderstand your question, you can just set

 Xq = 1.87 ;
 Yq = 2.9 ;

and have Zq with

 Zq = interp2( X, Y, Z, Xq, Yq ) ;

[Kyle Gao]

Yeah! This solved my question perfectly!