Re:

[Shai Ayal]

I think this is a real-world problem. It is probably the biggest flaw in 
the matlab language, making you write programs which use unintuitive and 
hard to understand tricks just to avoid for-loops. As a real world 
example, have a look at the code for hist.m in octave. Instead of a ~N 
for-loop, it uses NlogN sorting just because sort is done in C and thus 
is faster.

I think that for-loops are an essential part of any programming 
language, and avoiding them has unfortunately become the hallmark of 
good matlab programming. When conducting job interviews for positions 
for which matlab/octave is relevant, one of my questions is:

how would you calculate a 10 sample running average on a 100 element vector?

The answer should be trivial with a for-loop, but of course in the 
octave/matlab language it is not the "recommended" way. If I get the 
for-loop answer I immediately understand that this person has no 
real-life experience with octave/matlab.

Shai

p.s. This is not a rant against octave, rather against the matlab 
language. I understand that JIT for octave is probably not an achievable 
goal, and I will continue to use tricks because of the numerous other 
advantages of octave.

Arvid Rosén wrote:
> Jordi Gutierrez Hermoso wrote:
> > Of all the complaints I have heard about Octave, its slowness is the
> > one that stings the most painfully. Cuts deep. Real deep.
> >
> > So, I'm interested to know, any idea why this is happening? Why would
> > a simple for loop with no code to execute except running through all
> > the values of its iterator take orders of magnitude more in Octave
> > than in Matlab?
> >
> > Where are these benchmarks?
> >   
> Is this really a real-world problem? Do you people often run into 
> situations where the interpreter speed is the limiting factor. I don't 
> think I do, but I guess it depend on what kind of problems you are 
> working on.
> I just want to say that running empty for-loops is certainly not the way 
> to test the quality of Octave as a whole and it might not be a good way 
> to test the interpreter either. If you really depend on tiny for-loops, 
> you should probably rewrite your code anyway.
>
> /Arvid
>
>
>
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Octave is freely available under the terms of the GNU GPL.

Octave's home on the web:  http://www.octave.org
How to fund new projects:  http://www.octave.org/funding.html
Subscription information:  http://www.octave.org/archive.html
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