Changeset 351:2593e163e407 in lemon
 Timestamp:
 06/19/08 18:33:06 (10 years ago)
 Branch:
 default
 Children:
 352:0badf3bb38c2, 353:f8832dc16d45
 File:

 1 edited
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lemon/random.h
r280 r351 841 841 } 842 842 843 /// Lognormal distribution 844 845 /// Lognormal distribution. The parameters are the mean and the standard 846 /// deviation of <tt>exp(X)</tt>. 847 /// 848 double lognormal(double n_mean,double n_std_dev) 849 { 850 return std::exp(gauss(n_mean,n_std_dev)); 851 } 852 /// Lognormal distribution 853 854 /// Lognormal distribution. The parameter is an <tt>std::pair</tt> of 855 /// the mean and the standard deviation of <tt>exp(X)</tt>. 856 /// 857 double lognormal(const std::pair<double,double> ¶ms) 858 { 859 return std::exp(gauss(params.first,params.second)); 860 } 861 /// Compute the lognormal parameters from mean and standard deviation 862 863 /// This function computes the lognormal parameters from mean and 864 /// standard deviation. The return value can direcly be passed to 865 /// lognormal(). 866 std::pair<double,double> lognormalParamsFromMD(double mean, 867 double std_dev) 868 { 869 double fr=std_dev/mean; 870 fr*=fr; 871 double lg=std::log(1+fr); 872 return std::pair<double,double>(std::log(mean)lg/2.0,std::sqrt(lg)); 873 } 874 /// Lognormal distribution with given mean and standard deviation 875 876 /// Lognormal distribution with given mean and standard deviation. 877 /// 878 double lognormalMD(double mean,double std_dev) 879 { 880 return lognormal(lognormalParamsFromMD(mean,std_dev)); 881 } 882 843 883 /// Exponential distribution with given mean 844 884
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