COSPI 3CW "12 December 2007" "mathcw-1.00"

Table of contents


NAME

cospif, cospi, cospil, cospiw, cospiq, cospill, cospidf, cospid, cospidl, cospidll - cosine function

SYNOPSIS

cc [ flags ] -I/usr/local/include file(s) -L/usr/local/lib -lmcw [ ... ]

#include <mathcw.h>

extern float cospif (float x);

extern double cospi (double x);

extern long double cospil (long double x);

extern __float80 cospiw (__float80 x);

extern __float128 cospiq (__float128 x);

extern long_long_double cospill (long_long_double x);

extern decimal_float cospidf (decimal_float x);

extern decimal_double cospid (decimal_double x);

extern decimal_long_double cospidl (decimal_long_double x);

extern decimal_long_long_double cospidll (decimal_long_long_double x);

NB: Functions with prototypes containing underscores in type names may be available only with certain extended compilers.


DESCRIPTION

Compute the cosine of x, where the argument is measured in units of pi. Thus, cospi(x) = cos(pix). Unlike the normal cosine function, the argument is reduced exactly to the interval [-1,+1] by
r = modf(0.5 * x, NULL).
The function value is then cos(pir).

RETURN VALUES

If the argument is finite, its cosine is returned. Otherwise, a NaN is returned.

ERRORS

If the argument is a NaN, errno is set to EDOM, and the argument is returned. If the argument is +Infinity or -Infinity, errno is set to EDOM, and a quiet NaN is returned.

SEE ALSO

acos(3CW), acosp(3CW), acospi(3CW), asin(3CW), asinp(3CW), asinpi(3CW), atan(3CW), atan2(3CW), atan2p(3CW), atan2pi(3CW), atanp(3CW), atanpi(3CW), cos(3CW), cosp(3CW), cotan(3CW), cotanp(3CW), cotanpi(3CW), sin(3CW), sincos(3CW), sincosp(3CW), sincospi(3CW), sinp(3CW), sinpi(3CW), tan(3CW), tanp(3CW), tanpi(3CW).