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/* Copyright (C) 2010 Ion Torrent Systems, Inc. All Rights Reserved */
#ifndef RANDSCHRANGE_H
#define RANDSCHRANGE_H
/**
* Random number generator using Park & Millers numbers and Schrange's
* handling of integer overflow
*/
class RandSchrange {
public:
const static int RandMax = 2147483646; // RANDMAX = M - 1
RandSchrange(int seed = 1) {
SetSeed(seed);
}
void SetSeed(int seed) {
assert(seed != 0);
mNext = seed;
}
int Rand() {
mNext = A * (mNext % q) - r * (mNext / q);
if (mNext < 0) {
mNext += M;
}
return mNext;
}
private:
const static int A = 16807;
const static int M = 2147483647; // 2^31 - 1
const static int q = 127773; // M / A
const static int r = 2836; // M % A
int mNext;
};
#endif // RANDSCHRANGE_H
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