From maintainers-request at octave dot org Sun Jan 30 01:39:59 2005
Subject: Re: min function very slow?
From: Daniel J Sebald <daniel dot sebald at ieee dot org>
To: maintainers at octave dot org
Date: Sun, 30 Jan 2005 01:46:03 -0600

Daniel J Sebald wrote:

> John W. Eaton wrote:
>
>> If you have min and max in .oct files, then they are really defined in
>> the same file (minmax.oct) and the min.oct and max.oct files are just
>> additional links in the filesystem.  It seems that the second one
>> loaded is much slower.  I think this must be some accidental overhead
>> in checking whether the symbol needs to be reloaded.
>>
>
> But how would this account for Dmitri's example in a script file where 
> upon first run it's fine and thereafter is slow?
>
>>  The problem goes
>> away for me if I define min and max in separate files (i.e., create
>> min.cc and max.cc, each with only one DEFUN_DLD macro) or if I set
>> ignore_function_time_stamp = "all" (I'm not sure why setting it to
>> "system" fails, even when the min/max functions are installed in a
>> "system" directory).
>>  
>>
>
> But breaking it into separate files could simply be shuffling around 
> code as well. I.e., the problem moves somewhere else.


On second thought, your hypothesis seems correct.  rand() and randn() 
are similar to max/min, being in the same file.  I rewrote the function 
with rand/randn and got similar behavior:

octave:1> [loopt, randt, randnt] = rrt(10000)
loopt = 0.10696
randt = 0.36079
randnt = 0.35501
octave:2> [loopt, randt, randnt] = rrt(10000)
loopt = 0.10461
randt = 0.34843
randnt = 7.3243