Returns the complex arc hyperbolic tangent of its argument.

    This function is supported on OpenVMS Integrity servers and
    Alpha only.

    Format

      #include  <complex.h>

      double complex catanh  (double complex z);

      float complex catanhf  (float complex z);

      long double complex catanhl  (long double complex z);

1 - Argument

 z

    A complex value.

2 - Description

    The catanh functions compute the complex arc hyperbolic tangent
    of z, with branch cuts outside the interval [-1, +1] along the
    imaginary axis.

3 - Return Values

    n                  The complex arc hyperbolic tangent value, in
                       the range of a strip mathematically unbounded
                       along the real axis and in the interval
                       [-iπ/2, +iπ/2] along the imaginary
                       axis.