interp1 problem with Matlab2012

Hi,

I have problem with this function but only with the v2012.

"Error using griddedInterpolant The coordinates of the input points must be finite values; Inf and NaN are not permitted."

Somebody know about this problem according to a Matlab version? The same package of function run well under other version!

This is part of my function:

volx = interp1([stor(i, 1); inf], [v; 0], x, 'linear', 1);

Thanks a lot

Answer 1

[Jan]

The error message seems to be fair: How can the X-value of a signal equal Inf? It is meaningless to set the corresponding Y-value to zero. What do you expect as output value apart from the point stor(i)?

Answer 2

[Star Strider]

There is not enough information to be certain (and I don’t have access to R2012 on this machine), but it looks as though you want to extrapolate. The problem is that you are only dealing with a single scalar value in ‘stor’ (and possibly also ‘v’), so that will be a problem. Be sure ‘stor’ and ‘v’ are vectors of the same size, or your interpolation/extrapolation will fail.

Assuming that ‘x’ includes the value you want to extrapolate (that it is one element longer than ‘stor’ and ‘v’), use the 'extrap' option:

volx = interp1(stor(:, 1), v, x, 'linear', 'extrap');

See if that works.

[Star Strider]

@Vittoria — I do not understand the problem you want to solve. Please post some representative data, a detailed description of the problem, and what you want to do.

Answer 3

[Vittoria D'Avino]

Thanks a lot. I tried but I have the same problem :-( I try to explain the problem below:

Stor is a vector of 2 coloumn and finite number of rows (dose and volume for each patient 'i') x vector is shorter than raw dimension of 'stor' because my problem is that 'stor' have not the exact values of volume at fixed dose value.

I tried to substitute inf with 1 and I solved

volx = interp1([stor(i, 1); inf], [v; 0], x, 'linear', 1);

volx = interp1([stor(i, 1); 1], [v; 0], x, 'linear', 1);

In a second and similar function the problem is inverse: I have to extrapolate the value of dose at fixed value of volume but the similar solution is wrong...uff

dosex = interp1([v; inf], [stor(i, 1); 0], x, 'linear', MaxD(ddbsi));

I hope to be clear and sintetic.

Thanks a lot

[John D'Errico]

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