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Constrained random points on a circle: Difference between revisions
Constrained random points on a circle (view source)
Revision as of 13:31, 5 December 2010
, 13 years ago→{{header|PureBasic}}
(→{{header|Perl 6}}: pick(:replace) is now roll) |
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# # #
# # #</pre>
=={{header|Prolog}}==
Works with SWI-Prolog
<lang Prolog>:- use_module(library(clpfd)).
circle :-
bagof([X,Y], init(X,Y), BL),
length(BL, N),
length(L, 100),
maplist(choose(BL, N), L),
draw_circle(L).
% point selection
choose(BL, N, V) :-
I is random(N),
nth0(I, BL, V).
% to find all couples of numbers verifying
% 100 <= x^2 + y^2 <= 225
init(X1, Y1) :-
X in -15..15,
Y in -15..15,
X*X + Y*Y #>= 100,
X*X + Y*Y #=< 225,
label([X,Y]),
X1 is 10 * X + 200,
Y1 is 10 * Y + 200.
draw_circle(L) :-
new(D, window('Circle')),
send(D, size,size(400,400)),
forall(member([X,Y], L),
( new(C, circle(4)),
send(C, fill_pattern, colour(@default, 0, 0, 0)),
send(C, center(point(X,Y))),
send(D, display, C))),
send(D, open).
</lang>
=={{header|PureBasic}}==
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