db588d7b15
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@120 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
124 lines
2.4 KiB
Prolog
124 lines
2.4 KiB
Prolog
/*************************************************************************
|
|
* *
|
|
* YAP Prolog *
|
|
* *
|
|
* Yap Prolog was developed at NCCUP - Universidade do Porto *
|
|
* *
|
|
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
|
|
* *
|
|
**************************************************************************
|
|
* *
|
|
* File: random.yap *
|
|
* Last rev: 5/12/99 *
|
|
* mods: *
|
|
* comments: Random operations *
|
|
* *
|
|
*************************************************************************/
|
|
|
|
% original code from RA O'Keefe.
|
|
|
|
% This is algorithm AS 183 from Applied Statistics. I also have a C
|
|
% version. It is really very good. It is straightforward to make a
|
|
% version which yields 15-bit random integers using only integer
|
|
% arithmetic.
|
|
|
|
:- module(random, [
|
|
random/1,
|
|
random/3,
|
|
randseq/3,
|
|
randset/3,
|
|
getrand/1,
|
|
setrand/1
|
|
]).
|
|
|
|
:- load_foreign_files([random], [], init_random).
|
|
|
|
|
|
% random(R) binds R to a new random number in [0.0,1.0)
|
|
|
|
% random(L, U, R) binds R to a random integer in [L,U)
|
|
% when L and U are integers (note that U will NEVER be generated),
|
|
% or to a random floating number in [L,U) otherwise.
|
|
|
|
random(L, U, R) :- integer(L), integer(U), !,
|
|
random(X),
|
|
R is L+integer((U-L)*X).
|
|
random(L, U, R) :-
|
|
number(L), number(U), !,
|
|
random(X),
|
|
R is L+((U-L)*X).
|
|
|
|
/* There are two versions of this operation.
|
|
|
|
randset(K, N, S)
|
|
|
|
generates a random set of K integers in the range 1..N.
|
|
The result is an ordered list, such as setof might produce.
|
|
|
|
randseq(K, N, L)
|
|
|
|
generates a random sequence of K integers, the order is as
|
|
random as we can make it.
|
|
*/
|
|
|
|
|
|
randset(K, N, S) :-
|
|
K >= 0,
|
|
K =< N,
|
|
randset(K, N, [], S).
|
|
|
|
|
|
randset(0, _, S, S) :- !.
|
|
randset(K, N, Si, So) :-
|
|
random(X),
|
|
X * N < K, !,
|
|
J is K-1,
|
|
M is N-1,
|
|
randset(J, M, [N|Si], So).
|
|
randset(K, N, Si, So) :-
|
|
M is N-1,
|
|
randset(K, M, Si, So).
|
|
|
|
|
|
randseq(K, N, S) :-
|
|
randseq(K, N, L, []),
|
|
keysort(L, R),
|
|
strip_keys(R, S).
|
|
|
|
randseq(0, _, S, S) :- !.
|
|
randseq(K, N, [Y-N|Si], So) :-
|
|
random(X),
|
|
X * N < K, !,
|
|
random(Y),
|
|
J is K-1,
|
|
M is N-1,
|
|
randseq(J, M, Si, So).
|
|
randseq(K, N, Si, So) :-
|
|
M is N-1,
|
|
randseq(K, M, Si, So).
|
|
|
|
|
|
strip_keys([], []) :- !.
|
|
strip_keys([_-K|L], [K|S]) :-
|
|
strip_keys(L, S).
|
|
|
|
setrand(rand(X,Y,Z)) :-
|
|
integer(X),
|
|
integer(Y),
|
|
integer(Z),
|
|
X > 0,
|
|
X < 30269,
|
|
Y > 0,
|
|
Y < 30307,
|
|
Z > 0,
|
|
Z < 30323,
|
|
setrand(X,Y,Z).
|
|
|
|
getrand(rand(X,Y,Z)) :-
|
|
getrand(X,Y,Z).
|
|
|
|
|
|
|
|
|
|
|