MATLAB indexing question

Question

I have a matrix, for example

A = [ 1 2 3; 4 5 6; 7 8 9] ;

and a vector of size 1x3 which specifies which element in each row is the one I\

Answer 1

Here's a variation of Yochai's answer but without the transpose (this is also basically what SUB2IND does in Amro's answer):

 output = A((1:3)+3.*(vector-1));

Or for an array A of an arbitrary size:

 nRows = size(A,1);
 output = A((1:nRows)+nRows.*(vector-1));