The R Project SVN R

/*
 *  R : A Computer Langage for Statistical Data Analysis
 *  Copyright (C) 1995, 1996  Robert Gentleman and Ross Ihaka
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "Mathlib.h"

#ifndef HAVE_RINT
#define USE_BUILTIN_RINT
#endif

#ifdef USE_BUILTIN_RINT
#define RINT builtin_rint

    /* The largest integer which can be represented */
    /* exactly in floating point form. */

#define BIGGEST 4503599627370496.0E0        /* 2^52 for IEEE */

double builtin_rint(double x)
{
    double tmp;

    if (x != x) return x;           /* NaN */

    if (fabs(x) >= BIGGEST)         /* Already an integer */
        return x;

    if(x >= 0) {
        tmp = x + BIGGEST;
        return tmp - BIGGEST;
    }
    else {
        tmp = x - BIGGEST;
        return tmp + BIGGEST;
    }
}

#else
#define RINT rint
#endif

#define MAXPLACES 14

double rround(double x, double ndp)
{
    double pow10, sgn, intx;

    ndp = floor(ndp+0.5);
    if (ndp > MAXPLACES)
        ndp = MAXPLACES;
    pow10 = pow(10.0, ndp);
    sgn = 1.0;
    if(x < 0.0) {
        sgn = -sgn;
        x = -x;
    }
    if (ndp > 0.0) {
        intx = floor(x);
        x = x - intx;
    } else {
        intx = 0.0;
    }
    return sgn * (intx + RINT(x*pow10)/pow10);
}


double trunc(double x)
{
    if(x >= 0) return floor(x);
    else return ceil(x);
}