How does TIC TOC in matlab work?

Question

I am working with loops.I am using tic toc to check the time. I get different time when i run the same loop. The time is close to each other eg. 98.2 and 97.7. secondly when i reduce the size of the loop to half, i expect the time to change in half but it doesn't. Can anyone explain me how tic toc actually works? Thanks.

tic
for i=1:124
    for j=1:10
        for k=1:11
        end
   end
end
toc

Secondly i tried to use tic toc inside the loop as shown below. Will it return total time? I get a number but i cant verify if it actually is the total.

for i=1:124
    tic
    for j=1:10
        for k=1:11
        end
   end
   toc
end

Answer 1

tic and toc just measure the elapsed time in seconds. MATLAB has now JIT meaning that the actual time to compute cannot be estimated correctly. Matlab has (at least in this context) no real-time computation, so you basically always have different elapsed time for the same code.

Read this here, its nicely explained, hopefully it helps: http://www.matlabtips.com/matlab-is-no-longer-slow-at-for-loops/