MATLAB: Error when interpolating data code attached

debug4meinterpolationMATLAB

Im getting an error using the interp1, the workspace is attached. I think the issue is with te, where it jumps suddenly at indices 5139-5140. te is a time vector, eth is a concentration
    ethi = interp1 (te, eth, (tg+5))

Best Answer

I get an error when I run your code
    >> ethi = interp1 (te, eth, (tg+5));
    Error using griddedInterpolant
    The grid vectors are not strictly monotonic increasing.
    Error in interp1 (line 191)
            F = griddedInterpolant(X,V,method);
The message, The grid vectors are not strictly monotonic increasing., is clear enough.
    >> issorted( te )
    ans =
         1
    >> issorted( tg )
    ans =
         1
so far so good
    >> any(diff(te)==0)
    ans =
         1
    >> any(diff(tg)==0)
    ans =
         0
Thus, te is not strictly monotonic
    >> find(diff(te)==0)
    ans =
           11034
    >> te(11032:11036)'
    ans =
       1.0e+09 *
        1.4164    1.4164    1.4164    1.4164    1.4164
    >> format hex
    >> te(11033:11036)'
    ans =
       41d51b408950b780   41d51b408950be0e   41d51b408950be0e   41d51b408950c49c
    >> 
    >> figure, plot( te(11030:11040) )
&nbsp
&nbsp
Did you get the same or a different error message?
&nbsp
This works
    >> te(11034)= te(11035)-eps(te(11035));
    >> ethi = interp1 (te, eth, (tg+5));
    >> te(11033:11036)'
    ans =
       41d51b408950b780   41d51b408950be0d   41d51b408950be0e   41d51b408950c49c
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