stats_rand_gen_beta — Generates beta random deviate
说明
floatstats_rand_gen_beta
( float$a
, float$b
)
Returns a random deviate from the beta distribution with parameters A and
B. The density of the beta is x^(a-1) * (1-x)^(b-1) / B(a,b) for 0 < x
<. Method R. C. H. Cheng.