how can i determine the time it took to run an input?

n = length(V);  
S = zeros(n,2*n);
for i = 1:n
     for j = 2:i
         for k = 1:n
             S(i,j+k) = V(i);
         end
      end
end

First determine the number of instructions as a function of n, thus find T(n) for a single execution

of this algorithm?

[madhan ravi]

have you seen tic toc ? if you want to know the running time of a script.

[Jan]

@Morena: I've formatted your code to make it easier to read. You can do this by your own also.

"determine the number of instructions as a function of n"

This is not trivial. What exactly is "an instruction"?

Answer 1

[Jan]

You can use tic and toc, or more accurately timeit.