Re: octave loop slowness (was "")

[Joshua Rigler]

Wow, this is news to me, but it makes sense when I consider the 
differences I've experienced with various programs I've written to work 
in both ML and Octave.  Some, like a special interpolator I wrote last 
year that consisted of nothing but mathematical expressions and 
conditional blocks, run hundreds of times faster in ML, while other 
relatively loop-intensive functions saw almost no performance 
enhancement <insert viagra joke here> whatsoever.

So to be clear, ML basically reverts to one-line-at-a-time interpreter 
behavior when any user-defined function is inside the loop?  If this is 
the case, I whole-heartedly agree with you that the push to reproduce 
such behavior in Octave, at the expense of time lost on more important 
Octave objectives, is clearly a case of mistaken priorities.  If that 
much work is required to set up a loop that actually uses JIT, why not 
just write a .oct/.mex file?!?

-EJR

P.S.  I see Brendan Drew responded with similar, if better-informed, 
comments before I could click "send".  Oh well, I'll send this anyway, 
and maybe get more clarification regarding my question in paragraph two.


Paul Billings wrote:
> Many people compare octave to Matlab and don't realize that Matlab has
> invested mucho $$ in the JIT (just-in-time or "on the fly" compiling).
> While people are quick to say, "Matlab's JIT is great, why doesn't octave
> have one?", I personally don't think the JIT buys you much at all.  The
> primary flaw in Matlab's JIT is that you cannot call any user functions
> within the loop!
>
> Must structured programming is, well, structured, and has numerous calls to
> functions which call functions, etc.  For a sequence of calls to built-in
> functions, I will encapsulate this into a user function so that it is
> readable in the calling code and maintainable.  Whoops, I've just defeated
> Matlab's fancy JIT, but I live with it since scattered cut-and-pasted code
> blocks are unacceptable to me.
>
> To put it another way: I can pretend that octave has a JIT.  For my code,
> the "octave JIT" is about as effective as Matlab's -- meaning, it ain't.  I
> am happy that the people guiding this project understand that other features
> are of greater use.
>
> Paul



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