System Statistics

[c.calderon]

Hi all,

 

I am trying to run a simple experiment to determine how long it takes for GNUProlog to find the first solution in my solver..

 

This is what I am doing:

 

q:- statistics(key,_),

    check(Ld,End), statistics(key,[_,Y]),

    write(Ld), nl,

    write('time: '), write (Y), nl

 

.

I tried all four possible keys: user-time, system-time, cpu-time,real-time.

 

Results:

For the first three I get the following:

-the first solution

-time: 0

 

whereas when the key=real-time, time: [0-2]. That's sometimes, zero, others one or two.

 

I guess that when the key is user_time, system-time or cpu-time the time meassured is less than 1 ms.

But, why do I get apparentely random results when the key=real-time? According to the manual real-time is the absolute time elapsed since the start of Prolog but I am not sure that I understand what absolute time is.

Please, could anyone shed some light on this?

 

Many thanks...