tic - Start clock to measure performance

Syntax

Description

tic starts a stopwatch timer. Stop the timer with the toc function.

ticID = tic stores an identifier for the tic command, so that you can nest timing operations.

Tips

• Consecutive tic commands overwrite the internally recorded starting time.

• The clear function does not reset the starting time recorded by a tic command.

Output Arguments

ticID

Value to use as an input argument for a subsequent call to toc. The value has no independent meaning.

Examples

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 the minimum and average time to compute a summation of Bessel functions:

REPS = 1000;   minTime = Inf;   nsum = 10;
tic;

for i=1:REPS
   tStart = tic;   total = 0;
   for j=1:nsum, 
      total = total + besselj(j,REPS);
   end

   tElapsed = toc(tStart);
   minTime = min(tElapsed, minTime);
end
averageTime = toc/REPS;

See Also

clock | cputime | etime | profile | toc

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