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

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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 TRUE meaning to return NaN if status is an error

Author(s)

Robin K. S. Hankin

References

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

Examples

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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))