How to retrieve location values in a matrix

Suppose i have a matrix 4x6 i.e. 6 columns and 4 rows. I want to extract different location values from the matrix i.e. 3rd location from column 1, 4th location value from column 2, 1st location value from column 3 etc. ([ 3 4 1 5 2 2]). Then i have to add these column location values. Pls suggest the code.

Answer 1

[Chunru]

% Generate a 4X6 matrix
a = randi(10, 4, 6)

a = 4×6

7 6 6 8 8 6 5 6 4 7 5 8 2 8 6 7 1 1 2 6 9 3 6 6

% The index to each column
%idx = [ 3 4 1 5 2 2]       % 5 is not correct
idx = [ 3 4 1 4 2 2];

% Fund the corresponding linear index
ii = sub2ind([4, 6], idx, 1:6);
% Show the extracted data
a(ii)

ans = 1×6

2 6 6 3 5 8

sum(a(ii))

ans = 30

[Danish Nasir]

Actually i want to take indices of matrix a (4x6), and want to extract the values of some other matrix b (4x6) of same size with these indices.

Answer 2

[Sulaymon Eshkabilov]

% e.g.:
A = randi([0, 13], 4,6)

A = 4×6

8 12 8 6 10 4 9 2 1 3 7 1 2 6 5 5 0 1 3 3 10 10 9 1

A(3,1), A(4, 2), A(1,3)

ans = 2

ans = 3

ans = 8