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2 * Software License Agreement (BSD License)
4 * Copyright 2008-2009 Marius Muja (mariusm@cs.ubc.ca). All rights reserved.
5 * Copyright 2008-2009 David G. Lowe (lowe@cs.ubc.ca). All rights reserved.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
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19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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29 *************************************************************************/
44 * Seeds the random number generator
46 void seed_random(unsigned int seed);
49 * Generates a random double value.
51 double rand_double(double high = 1.0, double low=0);
54 * Generates a random integer value.
56 int rand_int(int high = RAND_MAX, int low = 0);
60 * Random number generator that returns a distinct number from
61 * the [0,n) interval each time.
63 * TODO: improve on this to use a generator function instead of an
64 * array of randomly permuted numbers
76 * n = the size of the interval from which to generate
79 UniqueRandom(int n) : vals(NULL) {
89 * Initializes the number generator.
91 * n = the size of the interval from which to generate
96 // create and initialize an array of size n
97 if (vals == NULL || n!=size) {
100 vals = new int[size];
102 for(int i=0;i<size;++i) {
106 // shuffle the elements in the array
107 // Fisher-Yates shuffle
108 for (int i=size;i>0;--i) {
109 // int rand = cast(int) (drand48() * n);
110 int rnd = rand_int(i);
111 assert(rnd >=0 && rnd < i);
112 swap(vals[i-1], vals[rnd]);
119 * Return a distinct random integer in greater or equal to 0 and less
120 * than 'n' on each call. It should be called maximum 'n' times.
121 * Returns: a random integer
127 return vals[counter++];