catanh(), catanhf(), catanhl()

Updated: October 26, 2022

Compute the complex inverse hyperbolic tangent


#include <complex.h>

double complex catanh( double complex z );

float complex catanhf( float complex z );

long double complex catanhl( long double complex z );


The value that you want to get the complex inverse hyperbolic tangent of.


The general-purpose math library.
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.


These functions compute the complex inverse hyperbolic tangent of z, with branch cuts outside the interval [−1; +1] along the real axis.

To check for error situations, use feclearexcept() and fetestexcept(). For example:


The complex inverse hyperbolic tangent of z, in the range of a half-strip mathematically unbounded along the real axis and in the interval [−iπ/2; +iπ/2] along the imaginary axis.

If z is: These functions return: Errors:
0 + 0i 0 + 0i
0 + NaNi 0 + NaNi
1 + 0i Inf + 0i FE_DIVBYZERO
x + Infi, for any finite positive x 0 + (π/2)i
x + NaNi, for any finite nonzero x NaN + NaNi
Inf + yi, for any finite positive y 0 + (π/2)i
Inf + Infi 0 + (π/2)i
Inf + NaNi 0 + NaNi
NaN + yi, for any finite y NaN + NaNi
NaN + Infi ±0 + (π/2)i, where the sign of the real part is unspecified
NaN + NaNi NaN + NaNi

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.


C11, POSIX 1003.1

Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes