casin(3)		    Library Functions Manual			casin(3)

NAME
     casin, casinf, casinl - complex arc sine

LIBRARY
     Math library (libm, -lm)

SYNOPSIS
     #include <complex.h>

     double complex casin(double complex z);
     float complex casinf(float complex z);
     long double complex casinl(long double complex z);

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))

ATTRIBUTES
     For  an  explanation  of the terms used in this section, see attributes(7).
     allbox; lbx lb lb l l l.  Interface Attribute Value T{ casin(), casinf(),
     casinl() T}   Thread safety  MT-Safe

STANDARDS
     C11, POSIX.1-2008.

HISTORY
     glibc 2.1.	 C99, POSIX.1-2001.

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

Linux man-pages 6.18		   2026-02-08				casin(3)