user_guide:tutorials:release:4.7:time

This tutorial is probably also available as a Jupyter notebook in the demo folder in the polymake source and on github.

Different versions of this tutorial: latest release, release 4.9, release 4.8, release 4.7, release 4.6, release 4.5, release 4.4, release 4.3, release 4.2, release 4.1, release 4.0, release 3.6, nightly master

Measure execution time

The benefit of using a standard programming language such as Perl is that one can use standard libraries for basic needs. For example, one can measure the runtime/execution time of a sequence of commands. Here is an example showing how to benchmark two different convex hull algorithms/codes on the same example.

> use Benchmark qw(:all);
> $r=rand_sphere(3,1000,seed=>1); $t=timeit(1,'$r->FACETS;'); print timestr($t), "\n";
> $r=rand_sphere(3,1000,seed=>1); $t=timeit(1,'prefer_now "beneath_beyond";$r->FACETS;'); print timestr($t);
1 wallclock secs ( 1.52 usr +  0.00 sys =  1.52 CPU) @  0.66/s (n=1)
1 wallclock secs ( 0.38 usr +  0.00 sys =  0.38 CPU) @  2.63/s (n=1)

Note that if timing a user function, you have to provide the application your function lives in:

> $t=timeit(1,'Polymake::polytope::rand_box(10,2000,1);'); print timestr($t);
0 wallclock secs ( 0.01 usr +  0.00 sys =  0.01 CPU) @ 100.00/s (n=1)

The above code does not work in a script file (.pl) because of polymake's modifications to Perl. You rather want to use something like this.

> use Benchmark qw(:all);
> use application 'polytope';
>     
> my $r=rand_sphere(3,100,seed=>1);
>     
> sub getfacets{
>   $r->FACETS;
> }
>    
> sub myBenchmark{
>   my $t=Benchmark::timeit(1,"getfacets"); 
>   print timestr($t);
> }
> myBenchmark;
 0 wallclock secs ( 0.02 usr +  0.00 sys =  0.02 CPU) @ 50.00/s (n=1)

Or this:

> use Benchmark qw(:all);
> use application 'polytope';
>     
> sub myBenchmark2($$) {
>     my ($d,$n)=@_;
>     my $r=rand_sphere($d,$n,seed=>1);
>     
>     my $t0= Benchmark->new;
>     $r->FACETS;
>     my $t1=Benchmark->new;
>     my $td1=timediff($t1,$t0);
>     print "FACETS: ".timestr($td1)."\n";
> }
> myBenchmark2(3,1000);
FACETS:  1 wallclock secs ( 1.46 usr +  0.00 sys =  1.46 CPU)
  • user_guide/tutorials/release/4.7/time.txt
  • Last modified: 2022/07/15 08:30
  • by 127.0.0.1