[Matlab] tic toc

tic Start a stopwatch timer.
    tic and TOC functions work together to measure elapsed time.
    tic, by itself, saves the current time that TOC uses later to measure the time elapsed between the two.
 
    TSTART = tic saves the time to an output argument, TSTART.

The numeric value of TSTART is only useful as an input argument for a subsequent call to TOC.

Example:

　　tstart = tic;
　　sum = 0;
　　for j=1:100
　　　　sum = sum + j;
　　end
　　telapsed = toc(tstart);