Error using griddedInterpolant The grid vectors do not define a grid of points that match the given values

Hey all, I keep getting this error message: "Error using griddedInterpolant The grid vectors do not define a grid of points that match the given values." Even though when I debug it step by step, the error appears nonsensically! Any help is greatly appreciated. Here is the code:

%READING DATA
b=400;h=400;fc=30;
Row=1472;
Data=xlsread('Thermocouples_2017-02-14_09-41-57.csv');
T=[20 100 200 300 400 500 600 700 800 900 1000 1100];
RF_fc_Calcar=[1 1 .97 .91 .85 .74 .6 .43 .27 .15 .06 .02];
Strain_c1Theta=[.0025 .004 .0055 .007 .01 .015 .025 .025 .025 .025 .025 .025];
Strain_cu1Theta=[.02 .0225 .025 .0275 .03 .0325 .035 .0375 .04 .0425 .045 .0475];
X_Channel=[0 5 10 42 75 400];
T_Conc=[Data(Row-4,8) Data(Row-4,9) Data(Row-4,12) Data(Row-4,11) Data(Row-4,10) Data(Row-4,22)];
c=200;

%DATA ANALYSIS
F_Conc=0;M_Conc=0;
for x=0.0000001:1:c

      T_c=interp1(X_Channel,T_Conc,x);
      Strain_c1Theta=interp1(T,Strain_c1Theta,T_c);
      T_c0=interp1(X_Channel,T_Conc,0);
      Strain_cEdge=interp1(T,Strain_cu1Theta,T_c0);
      Strain_c=Strain_cEdge*(1-x/c);
      fc_Calcar=interp1(T,RF_fc_Calcar,T_c)*fc;
      Stress=3*Strain_c*fc_Calcar/(Strain_c1Theta*(2+(Strain_c/Strain_c1Theta)^3));

      if x<h F_Conc=F_Conc+Stress*(1)*b;end
      Z_Conc=0.5*h-x;
      if x<h M_Conc=M_Conc+Stress*(1)*b*Z_Conc;end

      j=j+1;
  end

Answer 1

[Michelangelo Ricciulli]

Hi! The error comes in the second iteration of the for loop. In fact when you call

Strain_c1Theta=interp1(T,Strain_c1Theta,T_c);

the first time it works fine since T and Strain_c1Theta have the same dimensions. Then you overwrite it! So it will change dimension (becoming a scalar) while T is still a vector 1x12. I don't know the actual purpose of your function, so I don't know how to modify it to make it work properly.

[Zakaria Askif]

Thank you! I just realised that it should be named differently:

Strain_c1ThetaX=interp1(T,Strain_c1Theta,T_c);

Now it should work. Cheers!