Pseudo-random numbers/Splitmix64: Difference between revisions
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16408922859458223821
0: 20027 1: 19892 2: 20073 3: 19978 4: 20030
</pre>
=={{header|C++}}==
<syntaxhighlight lang="c++">
#include <iostream>
#include <cmath>
#include <vector>
class Splitmix64 {
public:
Splitmix64() { state = 0; }
Splitmix64(const uint64_t seed) : state(seed) { }
uint64_t next_int() {
uint64_t z = ( state += 0x9e3779b97f4a7c15 );
z = ( z ^ ( z >> 30 ) ) * 0xbf58476d1ce4e5b9;
z = ( z ^ ( z >> 27 ) ) * 0x94d049bb133111eb;
return z ^ ( z >> 31 );
}
double next_float() {
return next_int() / twoPower64;
}
private:
uint64_t state;
const double twoPower64 = pow(2.0, 64);
};
int main() {
Splitmix64 random(1234567);
for ( int i = 0; i < 5; ++i ) {
std::cout << random.next_int() << std::endl;
}
std::cout << std::endl;
Splitmix64 rand(987654321);
std::vector<uint32_t> counts(5, 0);
for ( int i = 0; i < 100'000; ++i ) {
uint32_t value = floor(rand.next_float() * 5.0);
counts[value] += 1;
}
for ( int i = 0; i < 5; ++i ) {
std::cout << i << ": " << counts[i] << " ";
}
std::cout << std::endl;
}
</syntaxhighlight>
{{ out }}
<pre>
6457827717110365317
3203168211198807973
9817491932198370423
4593380528125082431
16408922859458223821
0: 20027 1: 19892 2: 20073 3: 19978 4: 20030
</pre>
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