4.3BSD - /usr/src/usr.lib/libm/floor.c

   1: /*	@(#)floor.c	4.2	9/11/85 */
   2: 
   3: /*
   4:  * floor and ceil-- greatest integer <= arg
   5:  * (resp least >=)
   6:  */
   7: 
   8: double  modf();
   9: 
  10: double
  11: floor(d)
  12: double d;
  13: {
  14:     double fract;
  15: 
  16:     if (d<0.0) {
  17:         d = -d;
  18:         fract = modf(d, &d);
  19:         if (fract != 0.0)
  20:             d += 1;
  21:         d = -d;
  22:     } else
  23:         modf(d, &d);
  24:     return(d);
  25: }
  26: 
  27: double
  28: ceil(d)
  29: double d;
  30: {
  31:     return(-floor(-d));
  32: }
  33: 
  34: /*
  35:  * algorithm for rint(x) in pseudo-pascal form ...
  36:  *
  37:  * real rint(x): real x;
  38:  *	... delivers integer nearest x in direction of prevailing rounding
  39:  *	... mode
  40:  * const	L = (last consecutive integer)/2
  41:  * 	  = 2**55; for VAX D
  42:  * 	  = 2**52; for IEEE 754 Double
  43:  * real	s,t;
  44:  * begin
  45:  * 	if x != x then return x;		... NaN
  46:  * 	if |x| >= L then return x;		... already an integer
  47:  * 	s := copysign(L,x);
  48:  * 	t := x + s;				... = (x+s) rounded to integer
  49:  * 	return t - s
  50:  * end;
  51:  *
  52:  * Note: Inexact will be signaled if x is not an integer, as is
  53:  *	customary for IEEE 754.  No other signal can be emitted.
  54:  */
  55: #ifdef VAX
  56: static long Lx[] = {0x5c00,0x0};        /* 2**55 */
  57: #define L *(double *) Lx
  58: #else   /* IEEE double */
  59: static double L = 4503599627370496.0E0;     /* 2**52 */
  60: #endif
  61: double
  62: rint(x)
  63: double x;
  64: {
  65:     double s,t,one = 1.0,copysign();
  66: #ifndef VAX
  67:     if (x != x)             /* NaN */
  68:         return (x);
  69: #endif
  70:     if (copysign(x,one) >= L)       /* already an integer */
  71:         return (x);
  72:     s = copysign(L,x);
  73:     t = x + s;              /* x+s rounded to integer */
  74:     return (t - s);
  75: }

Defined functions

Defined variables

Defined macros