public Money Round(RoundingPlaces places, MidpointRoundingRule rounding, out Money remainder)
{
Int64 unit;
var placesExponent = getExponentFromPlaces(places);
var fraction = roundFraction(placesExponent, rounding, out unit);
var units = _units + unit;
remainder = new Money(0, _decimalFraction - fraction, Asset);
return(new Money(units, fraction, Asset));
}
private Int32 roundFraction(Int32 exponent, MidpointRoundingRule rounding, out Int64 unit)
{
var denominator = FractionScale / (Decimal)Math.Pow(10, exponent);
var fraction = _decimalFraction / denominator;
switch (rounding)
{
case MidpointRoundingRule.ToEven:
fraction = Math.Round(fraction, MidpointRounding.ToEven);
break;
case MidpointRoundingRule.AwayFromZero:
{
var sign = Math.Sign(fraction);
fraction = Math.Abs(fraction); // make positive
fraction = Math.Floor(fraction + 0.5M); // round UP
fraction *= sign; // reapply sign
break;
}
case MidpointRoundingRule.TowardZero:
{
var sign = Math.Sign(fraction);
fraction = Math.Abs(fraction); // make positive
fraction = Math.Floor(fraction + 0.5M); // round DOWN
fraction *= sign; // reapply sign
break;
}
case MidpointRoundingRule.Up:
fraction = Math.Floor(fraction + 0.5M);
break;
case MidpointRoundingRule.Down:
fraction = Math.Ceiling(fraction - 0.5M);
break;
case MidpointRoundingRule.Stochastic:
if (_rng == null)
{
_rng = new MersenneTwister();
}
var coinFlip = _rng.NextDouble();
if (coinFlip >= 0.5)
{
goto case MidpointRoundingRule.Up;
}
goto case MidpointRoundingRule.Down;
default:
throw new ArgumentOutOfRangeException("rounding");
}
fraction *= denominator;
if (fraction >= FractionScale)
{
unit = 1;
fraction = fraction - (Int32)FractionScale;
}
else
{
unit = 0;
}
return((Int32)fraction);
}
public Money Round(RoundingPlaces places, MidpointRoundingRule rounding = MidpointRoundingRule.ToEven)
{
Money remainder;
return(Round(places, rounding, out remainder));
}
