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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(+-_ + _i) returns Pi/2 - 0i.

     cacos(+-_ + 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                     December 11, 2006                    4th Berkeley Distribution