Optimization of functions delivered by MATLAB

Markus Buehren — Wed, 08 Aug 2007 08:55:45 -0400

Hi!

Occasionally I look into m-functions which are shipped with
Matlab and which are extremely often called in my code.
Often I find huge space for improvement. Let me give an
example with the function tripuls of the signal processing
toolbox (I don't know if I am allowed to post the code
here). It takes up to three arguments, but I never use the
third one. Anyway, the default parameter value is used in
the computations, causing unnecessary divisions and more. I
have written the following replacement which is much faster
when not using the third input argument:

error(nargchk(1,3,nargin));
if nargin < 2
  y = max(0, 1-2*abs(t));
elseif nargin < 3
  y = max(0, 1-2*abs(t)/Tw);
else
  y = tripuls(t, Tw, skew);
end

Ok, let me get to the point. Are there people at The
Mathworks involved with skimming through all files, looking
for possible optimizations in order to speed up Matlab a
little bit from one release to another? If not, would The
Mathworks pay me for doing this as a freelancer? :-)

Regards
Markus

Re: Optimization of functions delivered by MATLAB

John D'Errico — Wed, 08 Aug 2007 11:28:24 -0400

"Markus Buehren" <mb_matlabREMOVE@gmxTHIS.de> wrote in message
<f9c0eh$rft$1@fred.mathworks.com>...

> Ok, let me get to the point. Are there people at The
> Mathworks involved with skimming through all files, looking
> for possible optimizations in order to speed up Matlab a
> little bit from one release to another?

No, I doubt that there are people whos only job
is to constantly revisit all existing code, looking for
tweaks. If someone notices something that is
obviously bad, or if a comment comes in that
brings something to attention, yes they will
happily repair it. The fact is, any code that is
composed of millions of lines will have some
inefficiencies, some fragments that could be
improved.

As the author of many pieces of software, I can
point to tools that I wrote and rewrote many
times over many years, enhancing them each
time as I saw new tricks I could apply. But I can
assure you that many of the speed boosts that I
found would never have been turned up by some
random code screener.

The Mathworks pays their employees to know
the language, and know efficient ways to code in
that language. Plus they go through code reviews
of any code before it goes out, that will catch
most of the obvious problems. I'll bet they even
use mlint on their own code.

> If not, would The
> Mathworks pay me for doing this as a freelancer? :-)

No, I don't expect that TMW will pay you as a
freelance debugger and optimizer of their codes.
You can send in a bug report if you find a bug, or
an enhancement request if you see potential for
improvement. Or you can apply for a job formally
with their organization.

John

MATLAB Central Newsreader - Optimization of functions delivered by MATLAB

Optimization of functions delivered by MATLAB

Re: Optimization of functions delivered by MATLAB