NAME trig_sun, sincos, sind, cosd, tand, asind, acosd, atand, atan2d, sincosd, sinp, cosp, tanp, asinp, acosp, atanp, sin- cosp, sinpi, cospi, tanpi, asinpi, acospi, atanpi, atan2pi, sincospi - more trigonometric functions SYNOPSIS cc [ flag ... ] file ... -lsunmath -lm [ library ... ] #include <sunmath.h> void sincos(double x, double *s, double *c); double sind(double x); double cosd(double x); double tand(double x); double asind(double x); double acosd(double x); double atand(double x); double atan2d(double y, double x); void sincosd(double x, double *s, double *c); double sinpi(double x); double cospi(double x); double tanpi(double x); double asinpi(double x); double acospi(double x); double atanpi(double x); double atan2pi(double y, double x); void sincospi(double x, double *s, double *c); double sinp(double x); double cosp(double x); double tanp(double x); double asinp(double x); double acosp(double x); double atanp(double x); void sincosp(double x, double *s, double *c); DESCRIPTION sincos(x,s,c) allows simultaneous computation of *s:=sin(x) and *c:=cos(x). sind(x), cosd(x), and tand(x) return trigonometric functions of degree arguments. sind(x):= sin(x*n/180). The corresponding inverse functions compute asind(x):= asin(x)*180/n. Similarly atan2d(y,x):= atan2(y,x)*180/n. sinpi(x), cospi(x), and tanpi(x) avoid range-reduction issues because their definition sinpi(x):= sin(n*x) permits range reduction that is fast and exact for all x. The corresponding inverse functions compute asinpi(x):= asin(x)/n. Similarly atan2pi(y,x):= atan2(y,x)/n. sinp(x), cosp(x), and tanp(x) use PI/2, the double precision approximation to n/2, in the argument reduction step to reduce arguments exceeding PI/4 in magnitude to the range -PI/4 to PI/4 . The argument reduction step is accomplished by the fmod function; thus it is much faster than using the true value of n. The relation between sinp and sin is sinp(x):= sin(x*n/PI). The corresponding inverse functions asinp(x):= asin(x)*PI/n. Since PI/n is close to 1, we sim- ply return asin(x). The same applies to acosp(x) and atanp(x). SEE ALSO asin(3M), acos(3M), atan(3M), atan2(3M), cos(3M), sin(3M), tan(3M).
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