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/////////////////////////////////////////////////////////////////////////
// ftos.cc
//
// Copyright (c) 1996-2003 Bryce W. Harrington [bryce at osdl dot org]
//
//-----------------------------------------------------------------------
// License: This code may be used by anyone for any purpose
// so long as the copyright notices and this license
// statement remains attached.
//-----------------------------------------------------------------------
// This routine rounds a double using the "rounding rule", as expressed
// in _Advanced Engineering Mathematics_ by Erwin Kreyszig, 6th ed.,
// John Wiley & Sons, Inc., 1988, page 945.
//
// Discard the (k+1)th and all subsequent decimals.
// (a) If the number thus discarded is less than half a unit in the
// kth place, leave the kth decimal unchanged ("rounding down")
// (b) If it is greater than half a unit in the kth place, add one
// to the kth decimal ("rounding up")
// (c) If it is exactly half a unit, round off to the nearest *even*
// decimal.
// Example: Rounding off 3.45 and 3.55 by one decimal gives 3.4 and
// 3.6, respectively.
// Rule (c) is to ensure that in discarding exactly half a decimal,
// rounding up and rounding down happens about equally often,
// on the average.
///////////////////////////////////////////////////////////////////////
#include <math.h>
double rround(double x)
{
double xlow = floor(x);
if (x - xlow != 0.5000)
return floor(x + 0.5000);
else if ( floor(x/2.0) == xlow/2.0)
return xlow;
else
return xlow++;
}
// This version allows rounding to a specific digit
double rround(double x, int k)
{
if (k==0) return rround(x);
else return rround(x*pow(10,k)) / pow(10,k);
}
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