How do I get the value at a particular index?

So I have indices corresponding to values that I want. Is there a MATLAB function that would allow me to output the values when I input the indices of those values?

[James Tursa]

I don't understand. If k is the index, then A(k) is the value of A at index k. What else are you looking for?

[Katie]

If you have set of indicies in a vector, you can do A(vec) to return all the A values at that set of indicies rather than looking at each index individually:

X=2:2:10; %[2 4 6 8 10]
ind=[1,2,4]; %vector of indicies to output values for

A=X(ind); %A=[2 4 8]

[Walter Roberson]

There is a slightly different technique for the case where you have a list of row indices and a list of column indices, and you want to extract at corresponding pairs.

[Luis J Gilarranz]

@Walter Roberson, https://stackoverflow.com/questions/60475954/get-matrix-values-at-several-index-pairs-efficiently-matlab ??

[Walter Roberson]

Yes the techniques there are good, except I would not use the diag() one

Answer 1

[Siriniharika Katukam]

Hi

Consider A as the matrix, and x as indices, then

Values = A(x)

In case you need value of a 2-D matrix, define 'rowMatrix' which has the row indices and 'colMatrix' which has corresponding column indices, then

Values = A(rowMatrix, colMatrix)