Function psigamma

psigamma(x: number, deriv?: number, options?: RCompatibleOptions): number
Polygamma function, the derivative of order deriv of digamma. Equivalent to R's psigamma(). Takes a single number.

psigamma(-Infinity, deriv) is Infinity for odd deriv as in R, which treats it like the poles (NaN with rCompatible: false). Unlike R, which returns NaN for x < 0 with deriv >= 6 and where the result overflows, the value is computed there.
Parameters
- x: number
  Argument.
- deriv: number = 0
  Order of the derivative, an integer from 0 to 100 (rounded half to even; default 0, digamma).
- Optionaloptions: RCompatibleOptions
  rCompatible (default true).
Returns number
psi^(deriv)(x). At zero and the negative integers, Infinity for odd deriv and NaN for even. NaN if deriv is outside 0 to 100.
Example
```
psigamma(2, 2);  // -0.40411380631918853 (-2 (zeta(3) - 1))
```
- Defined in special/psigamma.ts:321