Iterative solving on Interpolated Data

So I am working with data extracted from pump maps and I want to be able to interpolate a solution from the data maps.

So to start I have done this for interpolation on the data

F = scatteredInterpolant(data1(:,1), data1(:,2), data1(:,3));
D = scatteredInterpolant(data2(:,1), data2(:,2), data2(:,3));
pr = F(comp_speed, comp_flow);
eff = D(pr, comp_flow);

% and the problem I don't know how to write around in matlab comes from the following
comp_flow = flow .* pr
% flow and comp_speed are calcuated from the same input matrix and are of the same size.
% I realize maybe my undersatnding is handicaped in my math skills. Any help is appreciated!

[Walter Roberson]

You have a logic loop there.

pr = F(comp_speed, comp_flow);

So pr is derived from comp_flow

comp_flow = flow .* pr

but comp_flow is derived from pr

It looks like the first input to F is speed, and the second is flow information, and the result is pressure ?

It looks likle the first input to D is pressure, and the second is flow information, and the result is efficiency ?

Once you have built F and D, what are the locations that you want to extrapolate over?

Are you needing to find some kind of steady-state comp-flow where you iterate through finding pr and using it to recalculate comp-_flow until the result changes less than some amount ?