I have a measured data set (x & y are inputs, z is the result at those measures):

x y z

0.036802 0.004908 0.07158

0.036802 0.022135 0.10095

0.130886 0.004908 0.09627

0.130886 0.022135 0.12560

I would like a formula for interpolation, to predict z for all input conditions x & y (within bounds), for example when x=0.0875 & y=0.0066.

I have tried some some formulas, but nothing is predicting with much accuracy.

Thanks for any help

J