TRIG(S)                  XENIX System V                   TRIG(S)



     Name
          sin, cos, tan, asin, acos, atan, atan2 - Performs
          trigonometric functions.

     Syntax
          #include <math.h>

          double sin (x)
          double x;

          double cos (x)
          double x;

          double tan (x)
          double x;

          double asin (x)
          double x;

          double acos (x)
          double x;

          double atan (x)
          double x;

          double atan2 (y, x)
          double x, y;

     Description
          sin, cos and tan return trigonometric functions of radian
          arguments.  The magnitude of the argument should be checked
          by the caller to make sure the result is meaningful.

          asin returns the arc sin in the range -/2 to /2.

          acos returns the arc cosine in the range 0 to .

          atan returns the arc tangent of x in the range -/2 to /2.

          atan2 returns the arc tangent of y/x in the range - to .

     See Also
          matherr(S)

     Diagnostics
          sin, cos, and tan lose accuracy when their argument is far
          from zero.  For arguments sufficiently large, these
          functions return zero when there would otherwise be a
          complete loss of significance.  In this case, a message
          indicating a TLOSS error is displayed on the standard error
          output.  For less extreme arguments causing partial loss of
          significance, a PLOSS error is generated but no error



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     TRIG(S)                  XENIX System V                   TRIG(S)



          message is displayed.  In both cases, errno is set to
          ERANGE.

          If the magnitude of the argument of asin or acos is greater
          than one, or if both arguments of atan2 are zero, zero is
          returned and errno is set to EDOM.  In addition, a message
          indicating a DOMAIN error is displayed on the standard error
          output.

          These error-handling procedures may be changed with the
          matther(S) function.

     Notes
          These routines must be linked with the -lm linker option.









































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