Issues with gpuArray Interpn

I have a series of 3 2D datasets (each one is 3x3 array):

f = rand(3, 3, 3);

In the above, the third dimension represents the dataset number.

These are essentially data at the following sample points for each dimension:

dimOneArray = [0.1 0.2 0.3];
dimTwoArray = [2 3 4];

For each dataset, I would like to interpolate the following targets in each dimension:

dimOneTarget = 0.15;
dimTwoTarget = 3;

In order to do this, I first generate ndgrid for both dimension sample points and then use interpn on the data f:

[dimOne, dimTwo] = ndgrid(dimOneArray, dimTwoArray);
serialInterp = interpn(dimOneArray, dimTwoArray, f, dimOneTarget, dimTwoTarget)

serialInterp = 
serialInterp(:,:,1) =

    0.5409


serialInterp(:,:,2) =

    0.6143


serialInterp(:,:,3) =

    0.6527

As can be seen, this results in an array with interpolants for each dataset as expect.

However when I run this using GPU, I get an error:

gpuInterp = interpn(dimOneArray, dimTwoArray, gpuArray(f), dimOneTarget, dimTwoTarget)

Error using gpuArray/interpn

The input arguments are invalid. For supported syntaxes, see help gpuArray.interpn.

Error in test4 (line 13)

gpuInterp = interpn(dimOneArray, dimTwoArray, gpuArray(f), dimOneTarget, dimTwoTarget);

Can someone see what the issue is?

Answer 1

[Manish]

Hi,

I was working on the similar usecase and encountered a similar issue. After trying several approaches, I found a workaround that might be helpful for you as well.

gpuInterp = interpn(dimOneArray, dimTwoArray, 1:3, gpuArray(f), dimOneTarget, dimTwoTarget, 1:3); 

I also checked the latest MATLAB R2021a documentation, and it provides clear understanding in the extended capabilities section. Please refer to the documentation below to know more about it.

https://www.mathworks.com/help/releases/R2021a/matlab/ref/interpn.html?searchHighlight=interpn&s_tid=doc_srchtitle#bvlxnx9-1

Hope it helps!