Reversing a 2D lookup table using S-fuction in Simulink

I would like to do a inversed 2D table lookup which was indicated as follows:

         _____________
    A--->|           |
         |2d-Looukup |--->C
    B--->|___________|

         ____________
    C--->| Reverse   |
         |  lookup   |--->B
    A--->|___________|

I got online an idea that works, for example:

A=[17.9 18.0 18.1 18.2]'; B=[0.4 0.5 0.6 0.7]; C=[67 89 95 108 74 92 110 123 80 97 115 127 84 106 119 135];

A1=18.046; %Z=interp2(A,B,C,A1,B); Z=interp2(A,B,C',A1,B); C1=105; B1=interp1(Z,B,C1);

My question is that how can I code this idea to a S-funtion that can be used in my Simulink Model where A1 and C1 would be inputs? My S-function is listed as follows but it didn't work - appreicate if anyone can help - thanks.

function V = TD(A1,C1) %#codegen A = [17.9; 18.0; 18.1; 18.2]; B = [0.4, 0.5, 0.6, 0.7]; C = [67, 89, 95, 108; 74, 92, 110, 123; 80, 97, 115, 127; 84, 106, 119, 135];

Z = interp2(A,B,C',A1,B); V = interp1 (Z, B, C1);

[Ryan Livingston]

Could you please elaborate on "but it didn't work"? Were there errors? If so what were they? Is the answer unexpected?

[Aaron]

Error said undefined variable - no results were generated...but those codes ran well in Matlab. Seems in S-function the interp1 and interp2 can be recognized.

Answer 1

[Titus Edelhofer]

Hi,

inverting will be possible only if the strict monoticity is given. If this is the case, you will end up with a usual 2D-Lookup again. I would suggest to compute the values within MATLAB and use the 2D-Lookup block instead of an S-Function.

Titus

[Aaron]

Yes, it is possible to invert the data - I established a reversed 2-D lookup table by writing a simple m-file program function in matlab. Still wondering if any trick for using S-function to deliever the reversed lookup data.

[Parth purohit]

how did you do it?