Start stopwatch timer
tic
timerVal = tic
tic
starts a stopwatch timer to measure
performance. The function records the internal time at execution of
the tic
command. Display the elapsed time with
the toc
function.
returns
the value of the internal timer at the execution of the timerVal
= tictic
command,
so that you can record time for simultaneous time spans.

Value of the internal timer at the execution of the 
Measure time to generate two random matrices and compute elementbyelement multiplication of their transposes.
tic A = rand(12000, 4400); B = rand(12000, 4400); toc C = A'.*B'; toc
Measure how the time required to solve a linear system varies with the order of a matrix:
t = zeros(1,100); for n = 1:100 A = rand(n,n); b = rand(n,1); tic; x = A\b; t(n) = toc; end plot(t)
Measure multiple time spans simultaneously using two pairs of tic/toc
calls.
To do this, measure the minimum and average time to compute a summation
of Bessel functions:
REPS = 1000; minTime = Inf; nsum = 10; tic; % TIC, pair 1 for i=1:REPS tStart = tic; % TIC, pair 2 total = 0; for j=1:nsum total = total + besselj(j,REPS); end tElapsed = toc(tStart); % TOC, pair 2 minTime = min(tElapsed, minTime); end averageTime = toc/REPS; % TOC, pair 1