Re: .oct function vs external program and text file exchange

[Przemek Klosowski]

On 01/14/2011 07:38 AM, Daniel Arteaga wrote:
> Hi all,
>
> I have an octave program which needs the results of external C++
> program, in Linux. For the moment the program is called from inside
> Octave with the 'system' function, and the communication is done via the
> exchange of text files. Everything works well.
>
> I'd like to be able to estimate the overhead of the external program
> call (and writing text files), vs the possible reconversion of the
> external program to an oct function.
>
> Before starting with the hassle of converting the program to an oct
> function (my C++ skills are very limited), I'd like to know whether I
> will get a significant gain.

Your workflow goes through five phases:

- writing of parameters in Octave,
- system() overhead of starting your executable,
- reading of data in your C++ code,
- calculation,
- output in C++ and input in Octave.

The actual amount of time spent in each one depends on your particular 
case, e.g. how much data is involved. Doing it in an .oct function would 
essentially reduce it to the calculation, and you can find out exactly 
how much time it takes by modifying your C++ to calculate and print the 
time from after reading the data to just before writing it out. Then, 
wrap your Octave code to write the params, call system() and read the 
results in the tic/toc pair, and subtract the C++ time from the
toc() value---it'll be your overhead.