Dynamic Random Variates (dynamic_random_variate)

Definition

An instance R of the data type dynamic_random_variate is a non-uniform random number generator. The generation process is governed by an array<int> w. Let $[l \, .. \, r]$ be the index range of w and let W = sum_i w[i] be the total weight. Then any integer $i \in [l \, .. \, h]$ is generated with probability w[i]/W. The weight function w must be non-negative and W must be non-zero. The weight function can be changed dynamically.

The include file is <LEDA/random_variate.h>

Creation

dynamic_random_variate	R(array<int> w);	creates an instance R of type dynamic_random_variate.

Operations

int	R.generate()	generates $i \in [l \, .. \, h]$ with probability w[i]/W.
int	R.set_weight(int i, int g)
		sets w[i] to g and returns the old value of w[i]. Precondition: $i \in [l \, .. \, h]$.