CACOSH(3) | Library Functions Manual | CACOSH(3)

# NAME

`cacosh`, `cacoshf`, `cacoshl` — complex inverse hyperbolic cosine

# SYNOPSIS

Math Library (libm, -lm)
`#include <complex.h>`

double complex
`cacosh`(double complex z);

float complex
`cacoshf`(float complex z);

long double complex
`cacoshl`(long double complex z);

# DESCRIPTION

The `cacosh`(), `cacoshf`() and `cacoshl`() functions compute the complex inverse hyperbolic cosine of z.

For all complex floating-point numbers z,

    cacosh(z) = i acos(z).

# RETURN VALUES

The `cacosh`(), `cacoshf`() and `cacoshl`() functions return the complex inverse hyperbolic cosine of z with imaginary part in the interval [-Pi, Pi], and non-negative real part.

# SEE ALSO

casinh(3), catanh(3)

# STANDARDS

The `cacosh`(), `cacoshf`() and `cacoshl`() functions conform to ISO/IEC 9899:1999 (“ISO C99”).

June 7, 2025 | Debian