casin man page

casin, casinf, casinl — complex arc sine


#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.


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))


These functions first appeared in glibc in version 2.1.


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

Interface Attribute Value
casin(), casinf(), casinl() Thread safety MT-Safe

Conforming to

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

See Also

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


This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at

Referenced By

asin(3), complex(7), csin(3).

The man pages casinf(3) and casinl(3) are aliases of casin(3).

2015-04-19 Linux Programmer's Manual