double psi(int derivate, double x);
Returns the polygamma function psi^((m))(x) of order derivate.
| # | Name | Type | Description |
|---|---|---|---|
| 1 | derivate | int | order m of the polygamma function; only 0 and 1 are supported. |
| 2 | x | double | argument; real positive. |
Remarks:
Computes the m-th derivative of the logarithm of the Gamma function:
psi^((m))(x) = (d^(m+1))/(dx^(m+1))lnGamma(x) .
Defined behavior: if derivate is 0 the function returns psi(x) (see Probabilities::digamma); if derivate is 1 it returns psi^((1))(x) (see Probabilities::trigamma). Both return NAN for x <= 0. Any other value of derivate is not supported and raises an EMtxVecException.
Declared in Dew::Math::Units::Probabilities · Dew.Math/Units.Probabilities.h · Cross-compiler