rand within dld function

[Dirk Eddelbuettel]

Hi Heber,

  Heber>  A simple question: How do I generate one uniform random number from
  Heber> within a .oct file function?  For some reason I can't make it work
  Heber> out.

The following code is a variation on what JWE once recommended for calling
functions in .m files from code in .oct files. After all, the mechanism is
the same -- you just have tell Octave's parser what you want to get executed.

So the following will call Octave's "rand" function with whatever argument is
in args(0). See below for how calls with '1' and '3' give just what rand(1)
and rand(3) would have generated.

Cheers, Dirk

-----------------------------------------------------------------------------
#include "config.h"
#include "oct-obj.h"
#include "oct-map.h"
#include "defun-dld.h"
#include "toplev.h"

DEFUN_DLD (call_oct_from_oct, args, nargout,
  "Should uniform random variable of dimension args(0).")
{
  string func = "rand";

  // read arg 0
  double x = args(0).double_value();

  // and put it into a new list
  octave_value_list arg;
  arg(0) = x;

  // function to call
  octave_value_list retval = feval (func, arg, 1);

  return retval;
}
-----------------------------------------------------------------------------


address@hidden:~/octave/oct/source> octave
Octave, version 2.0.13.94 (i386-pc-linux-gnu).
Copyright (C) 1996, 1997, 1998 John W. Eaton.
This is free software with ABSOLUTELY NO WARRANTY.
For details, type `warranty'.

octave:1> call_oct_from_oct(1)
ans = 0.63730
octave:2> call_oct_from_oct(3)
ans =

  0.10647  0.49915  0.57270
  0.47568  0.75489  0.65061
  0.86098  0.28920  0.88621



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