r93:f857981306ea
Mon, 17 Mar 2008 20:21:27
[Not Reviewed]
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@@ -798,16 +798,39 @@ |
| 798 | 798 |
///\param k shape parameter (<tt>k>0</tt>) |
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///\param x_min location parameter (<tt>x_min>0</tt>) |
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/// |
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double pareto(double k,double x_min) |
| 802 | 802 |
{
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return exponential(gamma(k,1.0/x_min)); |
| 804 | 804 |
} |
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/// Poisson distribution |
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/// This function generates a Poisson distribution random number with |
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/// parameter \c lambda. |
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/// |
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/// The probability mass function of this distribusion is |
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/// \f[ \frac{e^{-\lambda}\lambda^k}{k!} \f]
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/// \note The algorithm is taken from the book of Donald E. Knuth titled |
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/// ''Seminumerical Algorithms'' (1969). Its running time is linear in the |
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/// return value. |
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int poisson(double lambda) |
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{
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const double l = std::exp(-lambda); |
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int k=0; |
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double p = 1.0; |
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do {
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k++; |
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p*=real<double>(); |
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} while (p>=l); |
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return k-1; |
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} |
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///@} |
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///\name Two dimensional distributions |
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/// |
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///@{
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/// Uniform distribution on the full unit circle |
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@@ -28,9 +28,10 @@ |
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{
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double a=lemon::rnd(); |
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check(a<1.0&&a>0.0,"This should be in [0,1)"); |
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a=lemon::rnd.gauss(); |
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a=lemon::rnd.gamma(3.45,0); |
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a=lemon::rnd.gamma(4); |
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//Does gamma work with integer k? |
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a=lemon::rnd.gamma(4.0,0); |
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a=lemon::rnd.poisson(.5); |
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} |
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