CATANH(3)                BSD Library Functions Manual                CATANH(3)

NAME
     catanh -- complex inverse hyperbolic tangent function

SYNOPSIS
     double complex
     catanh(double complex z);

     long double complex
     catanhl(long double complex z);

     float complex
     catanhf(float complex z);

DESCRIPTION
     catanh(z) computes the inverse hyperbolic tangent of the complex float-
     ing-point number z, with branch cuts outside the interval [-1, 1] along
     the real axis.

     catanh() returns values in a strip of the complex plane with imaginary
     part in the interval [-Pi/2, Pi/2].

     For all complex floating point numbers z,

           catanh(conj(z)) = conj(catanh(z)).
           catanh(-z) = -catanh(z)

SPECIAL VALUES
     The symmetries of catanh() are used to abbreviate the specification of
     special values.

     catanh(0 ] 0i) returns 0 ] 0 i.

     catanh(0 ] NaN i) returns 0 ] NaN i.

     catanh(1 ] 0i) returns inf ] 0i and raises the divide-by-zero flag.

     catanh(x ] inf i) returns 0 ] Pi/2 i, for finite positive-signed x.

     catanh(x ] NaN i) returns NaN ] NaN i, for non-zero finite x.

     catanh(inf ] yi) returns 0 ] Pi/2 i, for finite positive-signed y.

     catanh(inf ] inf i) returns 0 ] Pi/2 i.

     catanh(inf ] NaN i) returns 0 ] NaN i.

     catanh(NaN ] yi) returns NaN ] NaN i, for finite y.

     catanh(NaN ] inf i) returns 0 ] Pi/2 i.

     catanh(NaN ] NaN i) returns NaN ] NaN i.

NOTES
SEE ALSO
     ctanh(3) complex(3)

STANDARDS
     The catanh() function conforms to ISO/IEC 9899:1999(E).

4th Berkeley Distribution      November 9, 2006      4th Berkeley Distribution