Probabilities::DirichletLambda Function

TCplx DirichletLambda(const TCplx &Z, int n = 64);

Dirichlet Lambda function.

#NameTypeDescription
1Zconst TCplx &complex value at which the Lambda function is evaluated.
2n = 64intnumber of terms used in the complex series approximation (default 64).

Returns: the Dirichlet Lambda function evaluated at the complex point Z.

Remarks:

The Dirichlet lambda function is defined by

lambda(z) = sum_(n=0)^(inf)1/((2n+1)^z) = (1-2^(-z))zeta(z) ,

and is related to the Riemann zeta and Dirichlet eta functions by zeta(z)/2^z=lambda(z)/(2^z-1)=eta(z)/(2^z-2).

Domain: any complex Z with 2^z != 2. Defined behavior: it is computed as lambda(z)=eta(z) (2^z-1)/(2^z-2) from Probabilities::DirichletEta; at z=1 (where 2^z=2) the result is complex infinity. On the real axis the imaginary part of the result is zero. Known value: lambda(2)=pi^2/8.

See Also: Probabilities::DirichletEta, Probabilities::RiemannZeta
Declared in Dew::Math::Units::Probabilities · Dew.Math/Units.Probabilities.h · Cross-compiler