How do I fix this interpolation error

I am trying to find the exact time constant on the plot but continue to get this error when trying to run the program

[Star Strider]

The ‘exprmenttime’ and ‘exprmentresult’ appear to be column vectors, so one optioon could be:

tr = unique([exprmenttime exprmentresult],'rows')

then separate ‘tr’ into the two sorted vectors later.

Similarly,

[tu,idx] = unique(exprmenttime);

exprmentresult = exprmentresult(idx);

could work.

The problem with the ‘desiredY’ assignment is that the interpolation is going to be interpolating ‘expermentresult’ by ‘temptimeconstant’ returning a value for ‘expermenttime’ as the output. I get the impression that you want the result of:

desiredY = interp1(expermenttime, exprmentresult, temptimeconstant);

instead.

However with neither the data nor code text that could be copied, pasted, and run, I cannot determine that.

.

Answer 1

[Torsten]

You can only inverse interpolate if your vector "exprmentresult" is strictly increasing or strictly decreasing. Since it contains duplicate values - as the error message from interp1 claims - MATLAB throws an error.