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SIN(3M)								       SIN(3M)

NAME
       sin,  cos,  tan,	 asin, acos, atan, atan2 - trigonometric functions and
       their inverses

SYNOPSIS
       #include <math.h>

       double sin(double x);

       double cos(double x);

       double tan(double x);

       double asin(double x);

       double acos(double x);

       double atan(double x);

       double atan2(double y, double x);

DESCRIPTION
       Sin, cos and tan return trigonometric functions of radian arguments x.

       Asin returns the arc sine in the range -pi/2 to pi/2.

       Acos returns the arc cosine in the range 0 to

       Atan returns the arc tangent in the range -pi/2 to pi/2.

       Atan2 computes the principal value of the arc tangent of y/x, using the
       signs  of both arguments to determine the quadrant of the return value.
       The arc tangent returned is in the range [- pi , + pi ]

ERROR (due to roundoff, etc.)
       Let P stand for the number stored in the computer  in  place  of	 pi  =
       3.14159	26535  89793  23846  26433  ... .  Let “trig” stand for one of
       “sin”, “cos” or “tan”.  Then the	 expression  “trig(x)”	in  a  program
       actually	 produces  an  approximation  to  trig(x∗pi/P), and “atrig(x)”
       approximates (P/pi)∗atrig(x).  The approximations are close.

       In the codes that run on	 other	machines,  P  differs  from  pi	 by  a
       fraction	 of  an	 ulp; the difference matters only if the argument x is
       huge, and even then the difference is  likely  to  be  swamped  by  the
       uncertainty  in x.  Besides, every trigonometric identity that does not
       involve pi explicitly is satisfied equally well regardless of whether P
       =      pi.	For	 instance,     sin(x)**2+cos(x)**2 = 1	   and
       sin(2x) = 2sin(x)cos(x) to within a few ulps no matter how  big	x  may
       be.   Therefore	the  difference	 between  P and pi is most unlikely to
       affect scientific and engineering computations.

SEE ALSO
       math(3M), hypot(3M), sinh(3M), sqrt(3M)

AUTHOR
       Robert P. Corbett, W. Kahan, Stuart I. McDonald,	 Peter Tang  and,  for
       the codes for IEEE 754, Dr. Kwok-Choi Ng.

4th Berkeley Distribution	August 1, 1992			       SIN(3M)
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