# CASIN

NAME

SYNOPSIS

DESCRIPTION

VERSIONS

ATTRIBUTES

CONFORMING TO

SEE ALSO

COLOPHON

## NAME

casin, casinf,
casinl - complex arc sine

## SYNOPSIS

**#include
<complex.h>**

**double
complex casin(double complex** *z***); **

float complex casinf(float complex *z***); **

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

Link with
*-lm*.

## DESCRIPTION

These functions
calculate the complex arc sine of *z*. If
*y = casin(z)*, then
*z = csin(y)*. The real part of *y* is
chosen in the interval [-pi/2,pi/2].

One has:

casin(z) = -i
clog(iz + csqrt(1 - z * z))

## VERSIONS

These functions
first appeared in glibc in version 2.1.

## ATTRIBUTES

For an
explanation of the terms used in this section, see
**attributes**(7).

## CONFORMING TO

C99,
POSIX.1-2001, POSIX.1-2008.

## SEE ALSO

**clog**(3),
**csin**(3), **complex**(7)

## COLOPHON

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