problem with interp1

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Stetson Spencer
Stetson Spencer on 27 Nov 2018
Answered: Bruno Luong on 27 Nov 2018
Hi, for some reason when I try to use the interp1 function it gives me an error "Error using griddedInterpolant. The grid vectors must contain unique points."
but in my code I already accounted for that by doing the following:
dnew = unique([dlrg dmed dsml]);
plrg = interp1(log10(dlrg),plrg,log10(dnew),'linear','extrap');
why is it ignoring the fact that I told it to use unique points?
  1 Comment
Adam Danz
Adam Danz on 27 Nov 2018
Perhaps your variables log10(dlrg),plrg do not have unique coordinates?

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Accepted Answer

Matt J
Matt J on 27 Nov 2018
It is dlrg that must contain unique points. There is no requirement for uniquness on dnew.

More Answers (2)

Stephen on 27 Nov 2018
Your definition of "dlrg" probably contains duplications. You aren't running unique on "dlrg" and that is the vector of values you are interpolating on. Also, you're assigning the variable name "plrg" to both the "Y" input and "yi" output of the function. That rarely ends well for me.

Bruno Luong
Bruno Luong on 27 Nov 2018
[x,i] = unique(log10(dlrg))
plrg = interp1(x,plrg(i),log10(dnew),'linear','extrap');


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