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c++11: Simplify random generation code using C++11.

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* src/misc/random.cc, src/misc/random.hh (srand, drand, mrand, rrand,
barand): Simplify using <random> from C++11.
(nrand, bmrand, prand): Remove these unused functions.
* src/tgbaalgos/randomgraph.cc: Adjust the use of barand.
* configure.ac: Do not check for srand48 and drand48.
This commit is contained in:
Alexandre Duret-Lutz 2013-12-18 23:42:25 +01:00
parent 7480470760
commit c64503fb33
4 changed files with 18 additions and 147 deletions
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59
src/misc/random.hh
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@ -24,7 +24,7 @@
# define SPOT_MISC_RANDOM_HH
# include "common.hh"
# include <cmath>
# include <random>
namespace spot
{
@ -55,69 +55,18 @@ namespace spot
/// \see mrand, rrand, srand
SPOT_API double drand();
/// \brief Compute a pseudo-random double value
/// following a standard normal distribution. (Odeh & Evans)
///
/// This uses a polynomial approximation of the inverse cumulated
/// density function from Odeh & Evans, Journal of Applied
/// Statistics, 1974, vol 23, pp 96-97.
SPOT_API double nrand();
/// \brief Compute a pseudo-random double value
/// following a standard normal distribution. (Box-Muller)
///
/// This uses the polar form of the Box-Muller transform
/// to generate random values.
SPOT_API double bmrand();
/// \brief Compute pseudo-random integer value between 0
/// and \a n included, following a binomial distribution
/// for probability \a p.
///
/// \a gen must be a random function computing a pseudo-random
/// double value following a standard normal distribution.
/// Use nrand() or bmrand().
///
/// Usually approximating a binomial distribution using a normal
/// distribution and is accurate only if <code>n*p</code> and
/// <code>n*(1-p)</code> are greater than 5.
template<double (*gen)()>
class barand
class SPOT_API barand : protected std::binomial_distribution<>
{
public:
barand(int n, double p)
: n_(n), m_(n * p), s_(sqrt(n * p * (1 - p)))
barand(int n, double p) : binomial_distribution(n, p)
{
}
int
rand() const
{
int res;
for (;;)
{
double x = gen() * s_ + m_;
if (x < 0.0)
continue;
res = static_cast<int> (x);
if (res <= n_)
break;
}
return res;
}
protected:
const int n_;
const double m_;
const double s_;
int rand();
};
/// \brief Return a pseudo-random positive integer value
/// following a Poisson distribution with parameter \a p.
///
/// \pre <code>p > 0</code>
SPOT_API int prand(double p);
/// @}
}
#endif // SPOT_MISC_RANDOM_HH