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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(+-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 |