127 lines
3.3 KiB
C
127 lines
3.3 KiB
C
/*
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* Copyright (c) 1985 Regents of the University of California.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms are permitted provided
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* that: (1) source distributions retain this entire copyright notice and
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* comment, and (2) distributions including binaries display the following
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* acknowledgement: ``This product includes software developed by the
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* University of California, Berkeley and its contributors'' in the
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* documentation or other materials provided with the distribution and in
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* all advertising materials mentioning features or use of this software.
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* Neither the name of the University nor the names of its contributors may
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* be used to endorse or promote products derived from this software without
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* specific prior written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#ifndef lint
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static char sccsid[] = "@(#)floor.c 5.7 (Berkeley) 10/9/90";
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#endif /* not lint */
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#include "mathimpl.h"
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vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */
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ic(L, 4503599627370496.0E0, 52, 1.0) /* 2**52 */
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#ifdef vccast
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#define L vccast(L)
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#endif
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double ceil();
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double floor();
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/*
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* floor(x) := the largest integer no larger than x;
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* ceil(x) := -floor(-x), for all real x.
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*
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* Note: Inexact will be signaled if x is not an integer, as is
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* customary for IEEE 754. No other signal can be emitted.
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*/
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double
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floor(x)
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double x;
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{
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double y;
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if (
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#if !defined(vax)&&!defined(tahoe)
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x != x || /* NaN */
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#endif /* !defined(vax)&&!defined(tahoe) */
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x >= L) /* already an even integer */
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return x;
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else if (x < (double)0)
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return -ceil(-x);
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else { /* now 0 <= x < L */
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y = L+x; /* destructive store must be forced */
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y -= L; /* an integer, and |x-y| < 1 */
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return x < y ? y-(double)1 : y;
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}
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}
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double
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ceil(x)
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double x;
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{
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double y;
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if (
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#if !defined(vax)&&!defined(tahoe)
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x != x || /* NaN */
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#endif /* !defined(vax)&&!defined(tahoe) */
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x >= L) /* already an even integer */
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return x;
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else if (x < (double)0)
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return -floor(-x);
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else { /* now 0 <= x < L */
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y = L+x; /* destructive store must be forced */
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y -= L; /* an integer, and |x-y| < 1 */
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return x > y ? y+(double)1 : y;
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}
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}
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#ifndef national /* rint() is in ./NATIONAL/support.s */
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/*
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* algorithm for rint(x) in pseudo-pascal form ...
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*
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* real rint(x): real x;
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* ... delivers integer nearest x in direction of prevailing rounding
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* ... mode
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* const L = (last consecutive integer)/2
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* = 2**55; for VAX D
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* = 2**52; for IEEE 754 Double
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* real s,t;
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* begin
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* if x != x then return x; ... NaN
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* if |x| >= L then return x; ... already an integer
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* s := copysign(L,x);
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* t := x + s; ... = (x+s) rounded to integer
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* return t - s
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* end;
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*
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* Note: Inexact will be signaled if x is not an integer, as is
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* customary for IEEE 754. No other signal can be emitted.
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*/
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double
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__rint(x)
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double x;
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{
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double s,t;
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const double one = 1.0;
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#if !defined(vax)&&!defined(tahoe)
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if (x != x) /* NaN */
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return (x);
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#endif /* !defined(vax)&&!defined(tahoe) */
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if (copysign(x,one) >= L) /* already an integer */
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return (x);
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s = copysign(L,x);
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t = x + s; /* x+s rounded to integer */
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return (t - s);
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}
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#endif /* not national */
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