How to get a y value from x and z values when data is in a grid

I have generated a surface based on reservoir elevation (x), spillway gate height opening (y), and discharge (z) based on a spillway rating curve. I would like to be able to enter a reservoir level (x) and a discharge(z) and get back an interpolated gate height (y) from the surface.

Does anybody know of a way to do this simply?

Thanks, Amanda

Answer 1

[Image Analyst]

If they're integers:

logicalIndexes = yourSurface(:, x) == zTarget  % Note: x is column so it's dimension #2.
y = find(logicalIndexes)

if yourSurface and zTarget are floating point, see the FAQ: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

Answer 2

[Star Strider]

My approach would be to experiment with interp2 or interp3, depending on what you find is most appropriate for your data.