CACOS(3)                 BSD Library Functions Manual                 CACOS(3)

NAME
     cacos -- complex inverse cosine function

SYNOPSIS
     double complex
     cacos(double complex z);

     long double complex
     cacosl(long double complex z);

     float complex
     cacosf(float complex z);

DESCRIPTION
     cacos(z) computes the inverse cosine of the complex floating-point number
     z, with branch cuts outside the interval [-1,1] along the real axis.

     cacos() returns values in a strip of the complex plane with unbounded
     imaginary part, and real part in the interval [0, Pi].

     For all complex floating point numbers z, cacos(conj(z)) =
     conj(cacos(z)).

SPECIAL VALUES
     The conjugate symmetry of cacos() is used to abbreviate the specification
     of special values.

     cacos(]-0 ] 0i) returns Pi/2 - 0i.

     cacos(]-0 ] NaN i) returns Pi/2 ] NaN i.

     cacos(x ] inf i) returns Pi/2 - inf i, for finite x.

     cacos(x ] NaN i) returns NaN ] NaN i, for finite nonzero x.

     cacos(-inf ] yi) returns Pi - inf i, for finite positive-signed y.

     cacos(inf ] yi) returns 0 - inf i, for finite positive-signed y.

     cacos(-inf ] inf i) returns 3Pi/4 - inf i.

     cacos(inf ] inf i) returns Pi/4 - inf i.

     cacos(]-inf ] NaN i) returns NaN ] inf i.

     cacos(NaN ] yi) returns NaN ] NaN i, for finite y.

     cacos(NaN ] inf i) returns NaN - inf i.

     cacos(NaN ] NaN i) returns NaN ] NaN i.

NOTES
SEE ALSO
     complex(3)

STANDARDS
     The cacos() function conforms to ISO/IEC 9899:1999(E).

4th Berkeley Distribution      November 9, 2006      4th Berkeley Distribution