psi
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constexpr Complex psi(const Complex &z) noexcept
Evaluates the psi function [1] for a complex input.
Parameters
- const Complex &z
A complex number.
Returns
- type Complex
A complex number.
The psi function is the derivative of the natural log of the gamma function. It is defined as:
\[\psi(z) = \frac{\Gamma'(z)}{\Gamma(z)}\]
Example
Complex z = 1.0 + 1_j;
std::cout << psi(z) << "\n";
Output:
0.0946503 + 1.07667j
References