/* $Id: round.c,v 1.1 2003/04/15 03:20:17 cher Exp $ */

/* This file is taken from Cephes math library */

/*
  Cephes Math Library Release 2.1:  January, 1989
  Copyright 1984, 1987, 1989 by Stephen L. Moshier
  Direct inquiries to 30 Frost Street, Cambridge, MA 02140
*/

#include "cephes.h"
#include "mconf.h"
#include <math.h>

/*							round.c
 *
 *	Round double to nearest or even integer valued double
 *
 *
 *
 * SYNOPSIS:
 *
 * double x, y, round();
 *
 * y = round(x);
 *
 *
 *
 * DESCRIPTION:
 *
 * Returns the nearest integer to x as a double precision
 * floating point result.  If x ends in 0.5 exactly, the
 * nearest even integer is chosen.
 * 
 *
 *
 * ACCURACY:
 *
 * If x is greater than 1/(2*MACHEP), its closest machine
 * representation is already an integer, so rounding does
 * not change it.
 */

double
cephes_round(double x)
{
  double y, r;

  /* Largest integer <= x */
  y = floor(x);

  /* Fractional part */
  r = x - y;

  /* Round up to nearest. */
  if( r > 0.5 )
    goto rndup;

  /* Round to even */
  if( r == 0.5 ) {
    r = y - 2.0 * floor( 0.5 * y );
    if( r == 1.0 ) {
    rndup:
      y += 1.0;
    }
  }

  /* Else round down. */
  return(y);
}

/*
 * Local variables:
 *  compile-command: "make -C .."
 * End:
 */