MATLAB: Spline fitting with repeated X’s

codespline fit

so here is my matlab code, and the problem is there is repeated x values and spline fit code doesn't work how can i make it so it only takes the first x and doesn't take the repeated ones? And im not good at matlab so, can you please show how to add the code or add it to the original code.
    load Pvst1.txt
    load Fvst1.txt
    tx = Pvst1(:,1);
    tF = Fvst1(:,1);
    x = Pvst1(:,2);
    F = Fvst1(:,2);
    tq=0:0.01:5.81;
    Fq = interp1(tF,F,tq,'spline');
    xq = interp1(tx,x,tq,'spline');
    plot(xq,Fq,'ko');
    hold on
    xlabel('Position (m)','Fontsize',24)
    ylabel('Force (N)','Fontsize',24)
    title('Force vs. Position for car, Part A','Fontsize',24)
    grid on
    hold on

Best Answer

tx and tF must be monotonically increasing without repeating values, but this is the case for your data. The x and F arrays do not matter. So everything should be o.k. for spline interpolation.
Do you get an error message ?
Replacing
tq=0:0.01:5.81;
by
tq=max(tx(1),tF(1)):0.01:min(tx(end),tF(end));
might help.
Best wishes
Torsten.
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