Interpolation

Hello,

I have table values,

Table:

For, X-interval = 360-380 x-units, Y-interval = 2200-2400 y-units

Z-value = 900 z-units

Calculation: X-calc Value = 371x-units, Y-calc Value = 2375 y-units

Z-calc Value = ?

I looked up interp2, interp3 but since the first row and column are basically ranges or intervals and are basically just references for Z-table value, it doesn't give an answer. It says the z value must be a 2-by-2 matrix where in fact my z table value is just 1-by-1 value.

[Jan]

It is easier to answer, if you post a working set of inputs.

What are "y-units"?

Answer 1

[Walter Roberson]

To clarify: if the combination holds of x in 360 to 380, and y in 2200 to 2400, then z should be the constant value 900? If so, use logical indexing.

Table = [360 380 2200 2400 900; 325 333 2817 2895 888];  %e.g.

z = NaN(size(X_calc));
for K = 1 : size(Table,1)
  idx = X_calc >= Table(K,1) & X_calc <= Table(K,2) & ...

          Y_calc >= Table(K,3) & Y_calc <= Table(K,4);
    z(idx) = Table(K,5);
  end

[Ferd]

Hey! Kewl Thanks! It works...