public static BigDecimal Add(BigDecimal value, BigDecimal augend, MathContext mc)
{
BigDecimal larger; // operand with the largest unscaled value
BigDecimal smaller; // operand with the smallest unscaled value
BigInteger tempBi;
long diffScale = (long)value.Scale - augend.Scale;
// Some operand is zero or the precision is infinity
if ((augend.IsZero) || (value.IsZero) || (mc.Precision == 0))
{
return(BigMath.Round(Add(value, augend), mc));
}
// Cases where there is room for optimizations
if (value.AproxPrecision() < diffScale - 1)
{
larger = augend;
smaller = value;
}
else if (augend.AproxPrecision() < -diffScale - 1)
{
larger = value;
smaller = augend;
}
else
{
// No optimization is done
return(BigMath.Round(Add(value, augend), mc));
}
if (mc.Precision >= larger.AproxPrecision())
{
// No optimization is done
return(BigMath.Round(Add(value, augend), mc));
}
// Cases where it's unnecessary to add two numbers with very different scales
var largerSignum = larger.Sign;
if (largerSignum == smaller.Sign)
{
tempBi = Multiplication.MultiplyByPositiveInt(larger.UnscaledValue, 10) +
BigInteger.FromInt64(largerSignum);
}
else
{
tempBi = larger.UnscaledValue - BigInteger.FromInt64(largerSignum);
tempBi = Multiplication.MultiplyByPositiveInt(tempBi, 10) +
BigInteger.FromInt64(largerSignum * 9);
}
// Rounding the improved adding
larger = new BigDecimal(tempBi, larger.Scale + 1);
return(BigMath.Round(larger, mc));
}
public static BigDecimal Pow(BigDecimal number, int n, MathContext mc)
{
// The ANSI standard X3.274-1996 algorithm
int m = System.Math.Abs(n);
int mcPrecision = mc.Precision;
int elength = (int)System.Math.Log10(m) + 1; // decimal digits in 'n'
int oneBitMask; // mask of bits
BigDecimal accum; // the single accumulator
MathContext newPrecision = mc; // MathContext by default
// In particular cases, it reduces the problem to call the other 'pow()'
if ((n == 0) || ((number.IsZero) && (n > 0)))
{
return(Pow(number, n));
}
if ((m > 999999999) || ((mcPrecision == 0) && (n < 0)) ||
((mcPrecision > 0) && (elength > mcPrecision)))
{
// math.07=Invalid Operation
throw new ArithmeticException(Messages.math07); //$NON-NLS-1$
}
if (mcPrecision > 0)
{
newPrecision = new MathContext(mcPrecision + elength + 1,
mc.RoundingMode);
}
// The result is calculated as if 'n' were positive
accum = BigMath.Round(number, newPrecision);
oneBitMask = Utils.HighestOneBit(m) >> 1;
while (oneBitMask > 0)
{
accum = BigMath.Multiply(accum, accum, newPrecision);
if ((m & oneBitMask) == oneBitMask)
{
accum = BigMath.Multiply(accum, number, newPrecision);
}
oneBitMask >>= 1;
}
// If 'n' is negative, the value is divided into 'ONE'
if (n < 0)
{
accum = Divide(BigDecimal.One, accum, newPrecision);
}
// The final value is rounded to the destination precision
accum.InplaceRound(mc);
return(accum);
}
public static BigDecimal Subtract(BigDecimal value, BigDecimal subtrahend, MathContext mc)
{
if (subtrahend == null)
{
throw new ArgumentNullException("subtrahend");
}
if (mc == null)
{
throw new ArgumentNullException("mc");
}
long diffScale = subtrahend.Scale - (long)value.Scale;
// Some operand is zero or the precision is infinity
if ((subtrahend.IsZero) || (value.IsZero) || (mc.Precision == 0))
{
return(BigMath.Round(Subtract(value, subtrahend), mc));
}
// Now: this != 0 and subtrahend != 0
if (subtrahend.AproxPrecision() < diffScale - 1)
{
// Cases where it is unnecessary to subtract two numbers with very different scales
if (mc.Precision < value.AproxPrecision())
{
var thisSignum = value.Sign;
BigInteger tempBI;
if (thisSignum != subtrahend.Sign)
{
tempBI = Multiplication.MultiplyByPositiveInt(value.UnscaledValue, 10) +
BigInteger.FromInt64(thisSignum);
}
else
{
tempBI = value.UnscaledValue - BigInteger.FromInt64(thisSignum);
tempBI = Multiplication.MultiplyByPositiveInt(tempBI, 10) +
BigInteger.FromInt64(thisSignum * 9);
}
// Rounding the improved subtracting
var leftOperand = new BigDecimal(tempBI, value.Scale + 1); // it will be only the left operand (this)
return(BigMath.Round(leftOperand, mc));
}
}
// No optimization is done
return(BigMath.Round(Subtract(value, subtrahend), mc));
}