Re: Mkoctfile and Fortran

[Przemek Klosowski]

On 02/21/2012 04:06 PM, Thomas D. Dean wrote:

>     dummy=system("fortran-app<  xx.in>  /dev/null");
>     dummy=system("cat XX.DAT | ./output.pl>  xx.dat");
>     load xx.dat;
>
> I want to do this in a loop, i=1:1000.  The file XX.DAT is 10MB
> Therefore, the desire to eliminate disk i/o.

Wrapping the fortran app so that it would return the results directly 
into Octave variables is of course the fastest way, but I would first 
recommend a simpler mod: change the fortran app to write the data to 
stdout and the comments (which you currently redirect to /dev/null, so 
maybe you don't need that at all) to  stderr (*), and then run it as:

[status,output]=system("fortran-app < xx.in | ./output.pl");

See, no files (although still slower than full wrapping of course)


> I can create a memory disk.  Maybe this will speed things up enough.

That probably won't help you much. On Linux the buffering of filesystems 
is typically pretty good so reasonably-sized files end up in disk 
buffers anyway and there's not much advantage to ramdisks.

p



(*) writing to stderr is not standard in Fortran AFAIK; depending on 
which compiler you use, something like this might work:

Open (Unit=3, File="/dev/stderr") ! Open Standard Error on Unit 3