Psi function

Psi (digamma) functions

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

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

References

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

Author(s)

Robin K. S. Hankin

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))