COS 3CW "09 March 2006" "mathcw-1.00"

Table of contents


NAME

cosf, cos, cosl, cosw, cosq, cosll, cosdf, cosd, cosdl, cosdll - cosine function

SYNOPSIS

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

#include <mathcw.h>

extern float cosf (float x);

extern double cos (double x);

extern long double cosl (long double x);

extern __float80 cosw (__float80 x);

extern __float128 cosq (__float128 x);

extern long_long_double cosll (long_long_double x);

extern decimal_float cosdf (decimal_float x);

extern decimal_double cosd (decimal_double x);

extern decimal_long_double cosdl (decimal_long_double x);

extern decimal_long_long_double cosdll (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 radians.

RETURN VALUES

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

Caution: Since the cosine is a periodic function on [0,2pi], arguments outside that range must be reduced to that range by subtracting a suitable multiple of 2pi. For large arguments, significance loss from that subtraction can lower the accuracy of the reduced argument, possibly to the point where there are no significant digits left. Accuracy is therefore unavoidably reduced for arguments of large magnitude. However, argument reduction in this implementation is exact for nondecimal bases, so accuracy is maintained over the entire floating-point range. In decimal arithmetic, when no meaningful argument reduction is possible, 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), cosdeg(3CW), cosp(3CW), cospi(3CW), cotan(3CW), cotandeg(3CW), cotanp(3CW), cotanpi(3CW), ereduce(3CW), eriduce(3CW), sin(3CW), sincos(3CW), sincosp(3CW), sincospi(3CW), sindeg(3CW), sinp(3CW), sinpi(3CW), tan(3CW), tandeg(3CW), tanp(3CW), tanpi(3CW).