compare the executive speed with Matlab

[John W. Eaton]

On  2-Jan-2009, Sergei Steshenko wrote:

| Sure, sure.
| 
| 1) 'octave':
| 
| octave:36> angles = pi * (1:1000000) / 1000000;tic; sins = sin(angles); toc
| Elapsed time is 0.49532795 seconds.

Please, use cputime.  Wall clock time is meaningless here as there
could be other things running on your system which affect the timing.

| 2) "C":
| 
| CPU time took 0.13 seconds at line number 74 of 'benchmark_sin.c' file
| Wallclock time took 0.130743 seconds at line #74 of 'benchmark_sin.c' file
| 
| 
| ; the file is attached ('benchmark_sin.c'), it contains the command line
| I used to compile it.
| 
| OK, so it's not 5 times, it's more than 3 times.
| 
| I think, however, that if I use table representation of 'sin', the ratio
| will be the 5 times I vaguely remember.

So, how did you build Octave, and what version is it?

Here is what I see with Octave 3.0.3 on a Debian AMD64 system.  My
copy of Octave is installed from the Debian package and used GCC 4.3.2
(Debian 4.3.2-1) with -O2 (and no other tricky optimization flags):

  octave:1> angles = pi * (1:1000000) / 1000000;
  octave:2> t = cputime (); sins = sin (angles); cputime () - t
  ans =  0.072004

Here is what I see with your code using the same version of GCC

  $ gcc -mtune=native -march=native -O3 sin-tst.c -lm -lrt
  $ ./a.out
  CPU time took 0.05 seconds at line number 74 of 'sin-tst.c' file
  Wallclock time took 0.0685717 seconds at line #74 of 'sin-tst.c' file

So I don't really see anything to fix here.

jwe