2 * Copyright (c) 1985, 1993
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33 * @(#)floor.c 8.1 (Berkeley) 6/4/93
38 vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */
40 ic(L, 4503599627370496.0E0, 52, 1.0) /* 2**52 */
47 * floor(x) := the largest integer no larger than x;
48 * ceil(x) := -floor(-x), for all real x.
50 * Note: Inexact will be signaled if x is not an integer, as is
51 * customary for IEEE 754. No other signal can be emitted.
60 #if !defined(vax)&&!defined(tahoe)
62 #endif /* !defined(vax)&&!defined(tahoe) */
63 x >= L) /* already an even integer */
65 else if (x < (double)0)
67 else { /* now 0 <= x < L */
68 y = L+x; /* destructive store must be forced */
69 y -= L; /* an integer, and |x-y| < 1 */
70 return x < y ? y-(double)1 : y;
81 #if !defined(vax)&&!defined(tahoe)
83 #endif /* !defined(vax)&&!defined(tahoe) */
84 x >= L) /* already an even integer */
86 else if (x < (double)0)
88 else { /* now 0 <= x < L */
89 y = L+x; /* destructive store must be forced */
90 y -= L; /* an integer, and |x-y| < 1 */
91 return x > y ? y+(double)1 : y;
95 #ifndef ns32000 /* rint() is in ./NATIONAL/support.s */
97 * algorithm for rint(x) in pseudo-pascal form ...
99 * real rint(x): real x;
100 * ... delivers integer nearest x in direction of prevailing rounding
102 * const L = (last consecutive integer)/2
104 * = 2**52; for IEEE 754 Double
107 * if x != x then return x; ... NaN
108 * if |x| >= L then return x; ... already an integer
109 * s := copysign(L,x);
110 * t := x + s; ... = (x+s) rounded to integer
114 * Note: Inexact will be signaled if x is not an integer, as is
115 * customary for IEEE 754. No other signal can be emitted.
123 const double one = 1.0;
125 #if !defined(vax)&&!defined(tahoe)
126 if (x != x) /* NaN */
128 #endif /* !defined(vax)&&!defined(tahoe) */
129 if (copysign(x,one) >= L) /* already an integer */
132 t = x + s; /* x+s rounded to integer */
135 #endif /* not national */