newlib/libm/mathfp/sf_atan.c

   1
   2 /* @(#)z_atanf.c 1.0 98/08/13 */
   3 /******************************************************************
   4  * Arctangent
   5  *
   6  * Input:
   7  *   x - floating point value
   8  *
   9  * Output:
  10  *   arctan of x
  11  *
  12  * Description:
  13  *   This routine returns the arctan of x.
  14  *
  15  *****************************************************************/
  16
  17 #include "fdlibm.h"
  18 #include "zmath.h"
  19
  20 float
  21 atanf (float x)
  22 {
  23   switch (numtestf (x))
  24     {
  25       case NAN:
  26         errno = EDOM;
  27         return (x);
  28       case INF:
  29         /* this should check to see if neg NaN or pos NaN... */
  30         return (__PI_OVER_TWO);
  31       case 0:
  32         return (0.0);
  33       default:
  34         return (atangentf (x, 0, 0, 0));
  35     }
  36 }
  37
  38 #ifdef _DOUBLE_IS_32BITS
  39 double atan (double x)
  40 {
  41   return (double) atangentf ((float) x, 0, 0, 0);
  42 }
  43
  44 #endif /* defined(_DOUBLE_IS_32BITS) */