CASIN(3) | Library Functions Manual | CASIN(3)

# NAME

`casin`, `casinf`, `casinl` — complex circular arc sine

# SYNOPSIS

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

double complex
`casin`(double complex z);

float complex
`casinf`(float complex z);

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

# DESCRIPTION

The `casin`(), `casinf`() and `casinl`() functions compute the complex circular arc sine of z.

For all complex floating-point numbers z,

    casin(z) = -i clog(iz + csqrt(1 - z^2)).

# RETURN VALUES

The `casin`(), `casinf`() and `casinl`() functions return the complex circular arc sine of z with unbounded imaginary part, and real part in the interval [-Pi/2, Pi/2].

# SEE ALSO

cacos(3), catan(3)

# STANDARDS

The `casin`(), `casinf`() and `casinl`() functions conform to ISO/IEC 9899:1999 (“ISO C99”).

June 7, 2025 | Debian