R: Psi (digamma) functions

Psi {gsl} | R Documentation

## Psi (digamma) functions

### Description

Psi (digamma) functions as per the Gnu Scientific Library, reference manual section 7.27. These functions are declared in header file `gsl_sf_psi.h`

### Usage

    psi_int(n, give=FALSE, strict=TRUE)
    psi(x, give=FALSE, strict=TRUE)
    psi_1piy(y, give=FALSE, strict=TRUE)
    psi_1_int(n, give=FALSE, strict=TRUE)
    psi_1(x, give=FALSE, strict=TRUE)
    psi_n(m, x, give=FALSE, strict=TRUE)

### Arguments

`m,n` | input: integer values
`x,y` | input: real values
`give` | Boolean with `TRUE` meaning to return a list of three items: the value, an estimate of the error, and a status number
`strict` | Boolean, with default `TRUE` meaning to return `NaN` if status is an error

### Author(s)

Robin K. S. Hankin

### References

http://www.gnu.org/software/gsl

### Examples

    x <- seq(from=1.2,to=1.25,by=0.005)
    cbind(x,psi(x),psi_1(x))
    #tabe 6.1, p267, bottom bit

    psi_int(1:6)
    psi(pi+(1:6))
    psi_1piy(pi+(1:6))
    psi_1_int(1:6)
    psi_n(m=5,x=c(1.123,1.6523))

[Package gsl version 2.1-6 Index]