inc_beta_ddb()

template<typename T >

T stan::math::inc_beta_ddb	(	T	a,
		T	b,
		T	z,
		T	digamma_b,
		T	digamma_ab
	)

Returns the partial derivative of the regularized incomplete beta function, I_{z}(a, b) with respect to b.

The power series used to compute the derivative tends to converge slowly when a and b are large, especially if z approaches 1. The implementation will throw an exception if the series have not converged within 100,000 iterations. The current implementation has been tested for values of a and b up to 12500 and z = 0.999.

Template Parameters

T	scalar types of arguments

Parameters

a	first argument
b	second argument
z	upper bound of the integral
digamma_b	value of digamma(b)
digamma_ab	value of digamma(b)

Returns

partial derivative of the incomplete beta with respect to b

Precondition

a >= 0

b >= 0

0 <= z <= 1

Definition at line 42 of file inc_beta_ddb.hpp.