{"id":2460,"date":"2024-05-07T11:00:14","date_gmt":"2024-05-07T15:00:14","guid":{"rendered":"https:\/\/blogs.mathworks.com\/matlab\/?p=2460"},"modified":"2024-05-07T11:00:14","modified_gmt":"2024-05-07T15:00:14","slug":"should-we-ban-tic-toc","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/matlab\/2024\/05\/07\/should-we-ban-tic-toc\/","title":{"rendered":"Should we ban tic\/toc?"},"content":{"rendered":"
Yesterday morning, I overheard my kids talking about a <\/span>tic\/toc<\/span><\/a> ban which surprised me because they are not MATLAB users and not particularly well connected at MathWorks. How would they know about something as big as this before me?<\/span><\/div>
\"Bantictoc.png\"<\/img><\/div>
The idea of <\/span>tic\/toc<\/span> is simple. <\/span>tic<\/span> starts a timer while <\/span>toc<\/span> stops it and reports the result. I use it all the time, both in day to day work and when discussing performance related issues. Here's an example for timing the generation of a random matrix<\/span><\/div>
tic <\/span>% start the timer<\/span><\/span><\/div><\/div>
data = rand(2000);<\/span><\/span><\/div><\/div>
toc <\/span>% stops the timer and reports the result<\/span><\/span><\/div>
Elapsed time is 0.025606 seconds.<\/div><\/div><\/div><\/div><\/div>
It's great and I love it! However, there are issues with using it for performance work. There's usually variation in the time of an individual run. The first time you run any command, for example, is often slower than all subsequent times for various reasons. There's also variation because of all the other programs your computer is running or maybe the CPU is switching to different clock speeds as it hits some internal thermal limit and so on.<\/span><\/div>
For this reason, it is usually much more beneficial to run the code many times and look at the statistics. For this reason, the <\/span>timeit<\/span><\/a> command was created. In order to perform a robust measurement, <\/span>timeit<\/span> calls the specified function multiple times and returns the median of the measurements. Here's how its used<\/span><\/div>
f = @() rand(2000);<\/span><\/span><\/div><\/div>
timeit(f)<\/span><\/span><\/div>
ans = 0.0219<\/div><\/div><\/div><\/div>
Run that several times and you'll get much less variation which is what you'd expect given that its more robust.<\/span><\/div>
Some of my fellow MathWorkers love <\/span>timeit<\/span> and I'm frequently advised to use it instead of <\/span>tic\/toc<\/span> in blog posts. <\/span>Loren Shure blogged about it back in 2013<\/span><\/a>, just after it was introduced, and she recently messaged me after I'd published something, essentially saying 'Great post kid, but you should ditch<\/span> tic\/toc<\/span> and use <\/span>timeit<\/span>\". You'll notice that my <\/span>recent post about SUNDIALS integration in MATLAB<\/span><\/a> uses <\/span>timeit<\/span> whenever I talk about performance. I'm trying to be good, honest I am! <\/span><\/div>
But banning <\/span>tic\/toc?<\/span> That's just too much! I reached out to MATLAB Head of Product, Michelle Hirsch, and asked what on earth was going on because here's the thing....<\/span><\/div>

I don't like MATLAB's timeit<\/span><\/h2>
I understand that <\/span>timeit<\/span> is more robust but I just don't like it and here's why:<\/span><\/div>