Re: time in computations

["Karim Belabas" <belabas@math.u-bordeaux1.fr>]

* Joerg Arndt [2005-09-26 17:57]:
> * Igor Schein <igor@txc.com> [Sep 26. 2005 04:53]:
> > On Sat, Sep 24, 2005 at 12:17:56AM -0400, Mak Trifkovic wrote:
> > > Can I program something along these lines in PARI: do calculation xxx for 
> > > 1 hr; if you don't finish within that time, quit.
> > > 
> > > Thanks,
> > > Mak
> > 
> > Workaround:
> > 
> > limit cputime 3600 # if you're using csh or derivatives
> > ulimit -t 3600 # if you're using Bourne shell or derivatives
> > 
> > Unfortunately it applies to the whole session, not each command.
> 
> Just start it in a subshell:
> (ulimit -t 3600; gp < script.gp; )
> 
> > There's no way to do it natively from inside gp.  I've brought up the
> > desirability of this feature in the past, it'd be nice to have it
> > accesible via default(), with default value 0 for unlimited. 

Here's a one-liner inspired by the above discussion:

  timeout(T,E) = extern( Str("ulimit -t ", T, "; echo \"", E, "\" | gp -q -f") )


  (18:11) gp > timeout(10, "1 + 1")    \\ allow 10 sec to compute 1 + 1
  time = 0 ms.
  %1 = 2
  (18:11) gp > timeout(10, "bnfinit(x^30 - 2)")
  (18:12) gp > \\ empty output

[ Don't forget the quotes, otherwise the argument is fully evaluated before
  the "limited" subshell is launched ]

Cheers,

    Karim.
-- 
Karim Belabas                  Tel: (+33) (0)5 40 00 26 17
Universite Bordeaux 1          Fax: (+33) (0)5 40 00 69 50
351, cours de la Liberation    http://www.math.u-bordeaux.fr/~belabas/
F-33405 Talence (France)       http://pari.math.u-bordeaux.fr/  [PARI/GP]