Selecting an element from each column of a matrix using another matrix

I have a 130x87 matrix (A) and I need to select an element from each column based on the numbers in a 1x87 matrix (B). So if the first number in matrix B is 12, I need the 12th number in the first column of matrix A.

Answer 1

[Stephen23]

Use sub2ind:

>> A = [0,1,2;3,4,5;6,7,8;9,10,11] % your matrix
A =
    0    1    2
    3    4    5
    6    7    8
    9   10   11
>> B = [2,4,3]; % the rows you want
>> X = sub2ind(size(A),B,1:size(A,2));
>> A(X) % get the values
ans =
    3   10    8

Answer 2

[Azzi Abdelmalek]

%Example
A= randi(10,5,6)
B =randi(5,1,6)
%---------------------
[n,m]=size(A);
idx=B+(0:n:n*(m-1))
out=A(idx)