problem with interp1

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?

[Adam Danz]

Perhaps your variables log10(dlrg),plrg do not have unique coordinates?

Answer 1

[Matt J]

It is dlrg that must contain unique points. There is no requirement for uniquness on dnew.

Answer 2

[Stephen]

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.

Answer 3

[Bruno Luong]

[x,i] = unique(log10(dlrg))
plrg = interp1(x,plrg(i),log10(dnew),'linear','extrap');