How to specify a row and column in an array

So I have a 5x80 array and want to write a section of code which subtracts row 1, column 1 from row 2 column 1. How might I do that? I already tried using the (x,:) technique.

This is my attempt:

u1 = u(1,:1);
u2 = u(2,:1);

Answer 1

[KSSV]

A = rand(5,80) ; 
iwant = A(1,1)-A(2,1)

What you tried:

u1 = u(1,:1);

:1 is not valid. Simply you need to index bu u(r,c).

u(1,:)  % gives entire first row 
u(:,1) % gives entire first column