explicit weibull_distribution( RealType a = 1.0, RealType b = 1.0 );
(1) (since C++11)
explicit weibull_distribution( const param_type& params );
(2) (since C++11)

Constructs a new distribution object. The first version uses a and b as the distribution parameters, the second version uses params as the distribution parameters.

[edit] Parameters

a - the a distribution parameter (shape)
b - the b distribution parameter (scale)
params - the distribution parameter set