How to measure FLOPS of a MatLab function

Hello, I recently installed a FLOPS toolbox called Lightspeed by Tom Minka. http://research.microsoft.com/en-us/um/people/minka/software/lightspeed/

But I have to rewrite the code so that every operation I want to be counted is specifically measured, such as by changing multiplication calls to flops_mult() calls.

How to measure FLOPS of a MatLab function, for example, fft or interp ?

Will I be able to calculate this in MATLAB 5 using the flops function?

Answer 1

[Walter Roberson]

You cannot use the Lightspeed toolbox to count FLOPS of built-in MATLAB functions. To use Lightspeed you have to add function calls to everything that is to be measured, along the lines of "Hey, I'm about to do an algebraic matrix multiplication of an N x M left side and M x P right side". The toolbox has no idea how many flops an fft takes.

Very old versions of MATLAB had a flops() function; that was back in the days when counting flops was still a vaguely relevant measurement of performance. I do not know how it was implemented or whether it covered everything. If it hooked into hardware cycle counters then it would be useless with modern CPUs.