Need help to compute running time

Question

I have made following matlab code for computing cpu time of matlab inbuilt function pinv(A) to compute the Pseudo inverse of a given matrix. I had runed the matlab code 1000 times & calculated the mean of the results.

Matlab code

A = rand(10) % given randomly generated matrix of order 10
REPS = 1000; % taking thousand times repetitions 

minTime = Inf; 

tic
for i=1:REPS
    tstart = tic;  

    x1=pinv(A)

    telapsed = toc(tstart);

    minTime = min(telapsed,minTime);
end

execTime = toc; % total execution time

averageTime = execTime/REPS

I am not sure whether my program is correct or not? I have to use these results for my project work. Could anybody help me with this. I would be very much thankful to you.

Answer 1

(Copied from above comments) I edited your code. I changed it slightly. execTime is the total execution time. averageTime is the average time to calculate the pseudoinverse. minTime is the minimum time for one iteration. You are also likely to get more accurate results if each iteration takes longer (See here for issues when the execution time is too short). The easiest way to do this is to increase the size of A, such as A=rand(100). Depending on your machine, this still may not be large enough.

The edited code will work as you desire. As I said, you may not experience accurate results for the timing with A so small in size. As I suggested above, make the coefficient matrix A larger, so that the total execution time is longer for each iteration. (I will post these comments as an answer.)