Getting coefficient from a chebfun (chebcoeffs2-chebpoly)

I worte the following code to get an apprroximation of a compressor map:

clear

clc

close all

 

FlowMeasurements = chebpts(5,[-0.2,0.8]); % x needed by Chebishev

SpeedMeasurements = chebpts(5,[25000, 55000]);  %speeds needed by Chebyshev

 

CompressorMapMatrix =[

 

    1.5805    1.2092    1.1402    1.0234    1.0095

    1.6553    1.2840    1.2564    1.0565    1.0287

    1.9070    1.5357    1.7124    1.2518    1.1505

    2.2873    1.9160    2.4317    1.7374    1.4732

    2.4935    2.1222    2.8189    2.0728    1.7064]; % thats the datas points Chebishev needs

 

FlowVector = -0.2:0.01:0.8;

approximationResult  =  chebfun2(CompressorMapMatrix,[ -0.2 0.8 25000 55000]);

 

%% Plot chebfun not scaled

for i=1:length(SpeedMeasurements)  

figure(2)

plot(approximationResult(FlowVector, SpeedMeasurements(i)));

hold on

grid on

end

Now I need the coefficient a_ij because I need to use this equation:

and also the T_i/j polinomium:

I know I might have to use

chebcoeffs2

and

chebpoly

but really no clue on how. I wonder if someone can help me out for this thing.