COSPI(3)               FreeBSD Library Functions Manual               COSPI(3)

NAME
     cospi, cospif, cospil - half-cycle cosine functions

LIBRARY
     Math Library (libm, -lm)

SYNOPSIS
     #include <math.h>

     double
     cospi(double x);

     float
     cospif(float x);

     long double
     cospil(long double x);

DESCRIPTION
     The cospi(), cospif(), and cospil() functions compute the cosine of <pi>
     x x.  and measure angles in half-cycles.

RETURN VALUES
     The cospi(), cospif(), and cospil() functions returns cos(<pi> x x).  If
     |x| >= 2^(p - 1) where p is the floating-point precision of x, then the
     returned value is 1 and it has no significance.

SPECIAL VALUES
             cospi(+-0) returns 1.

             cospi(+-n/2) returns 0 for positive integers n.

             cospi(n) returns 1 for even integers n.

             cospi(n) returns -1 for odd integers n.

             cospi(+-<infinity>) return an NaN and raises an FE_INVALID
             exception.

             cospi(NaN) return an NaN and raises an FE_INVALID exception.

SEE ALSO
     cos(3), fenv(3), math(3), sin(3), sinpi(3), tan(3), tanpi(3)

AUTHORS
     The half-cycle trignometric functions were written by Steven G. Kargl
     <kargl@FreeBSD.org>.

STANDARDS
     These functions conform to IEEE Std 754tm-2008 , "IEEE Standard for
     Floating-Point Arithmetic" and to ISO/IEC TS 18661-4 , "Information
     technology -- Programming languages, their environments, and system
     software interfaces -- Floating-point extensions for C" -- Part 4:
     Supplementary functions.

FreeBSD 13.1-RELEASE-p6          April 1, 2017         FreeBSD 13.1-RELEASE-p6