Any good resources on how to use "Matrix Interpolation" block in simulink?

So I want to use the "Matrix Interpolation" block in simulink, but I am confused as to how to actually use it and the only resource I could find on it was the help page:

https://www.mathworks.com/help/simulink/ref_extras/matrixinterpolation.html

I have some 5x2 matrices I want to select based on two integer indices with a "nearest" selection (so if I pass in the indices (0.6, 2.7) I want to select the matrix specified by the indices (1,3)). I was wondering, how can this be done? I mainly dont know how to pass in the matrices such that it aligns with the "Table data" input in the matrix interpolation block parameter menu.

Answer 1

[Fangjun Jiang]

What you need is the "2-D Lookup Table" block. Drag that from the library and select "Nearest" at the "Algorithm" tab. The Help page gives you the general n-D Lookup Table block, which sometimes is hard to understand.

The "Matrix Interpolation" block can be regarded as the expansion of the Lookup Table block. It allows you to provide matrix input (as index input) to get multiple points at a time.

[Vinh]

Sorry, I am still confused as to how to use a 2D Lookup Table. All the examples I found on it only have the table specify a single scalar output, but I need the output to be a 5 by 2 matrix. Is there a way to do this with the 2D Lookup Table?

[Fangjun Jiang]

I am confused. So you have multiple 5x2 matrices and you want to pick out a particular one? How does indices (0.6, 2.7) and then its nearest value (1,3) decide which matrix to pick?

[Vinh]

So I have a 5 by 2 matrix called A_(1,1) associated with the index (1,1), and another 5 by 2 matrix called A_(2,3) associated with the index (2,3), etc. In my MATLAB script, I have the matrices saved in a cell array A_cellArray, such that given two indices ind1 and ind2 I can select the 5 by 2 matrix I want using A_cellArray{ind1,ind2}. I want to replicate that functionality in Simulink such that during simulation, with some calculations to specify integers ind1 and ind2 I want my model to then be able to select the correct corresponding 5 by 2 matrix given by A_cellArray{ind1,ind2}.

The nearest thing can be ignored if that makes things easier to implement, since I guess I can just specify separately a block of Simulink that converts my calculations to a nearest index. Also, thank you for the help.

[Fangjun Jiang]

Okay, use a Selector block to select data from A_, which is a multi-dimension array. Round your indices to provide as the 3rd and 4th dimension input.

A_=rand(5,2,2,3);
A_(:,:,1,1)

ans = 5x2

0.3705 0.0462 0.7544 0.8008 0.1469 0.7097 0.2789 0.6740 0.9496 0.7416

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A_(:,:,2,3)

ans = 5x2

0.0886 0.8163 0.2355 0.7434 0.5893 0.3653 0.0105 0.1403 0.6884 0.2630

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[Vinh]

Awesome, many thanks!