public LargeInteger Pow(ulong power)
{
LargeInteger.Logger.Debug($"Entering Pow. this: {this}, power: {power}");
this.Ensure();
if (this == 0 && power == 0)
{
throw new DivideByZeroException("LargeInteger: divide by zero");
}
var result = new LargeInteger(1);
for (var i = 0uL; i < power; i++)
{
result *= this;
}
LargeInteger.Logger.Debug($"Exiting Pow. result: {result.PrintLargeInteger()}");
return result;
}
/// <summary>
/// Divides the current instance by the divisor.
/// </summary>
/// <param name="divisor">Divisor</param>
/// <returns>Tuple<Quotient, Remainder></returns>
public Tuple<LargeInteger, LargeInteger> Divide(LargeInteger divisor)
{
LargeInteger.Logger.Debug($"Entering Divide. this (dividend): {this.PrintLargeInteger()}, divisor: {divisor.PrintLargeInteger()}");
this.Ensure().Ensure(ref divisor);
if (this < divisor)
{
return new Tuple<LargeInteger, LargeInteger>(0, this);
}
// This is long division.
var quotient = new LargeInteger { data = new List<uint>() };
var testDividend = new LargeInteger { data = new List<uint>() };
int dividendPosition = this.data.Count - 1;
for (int i = 0; i < divisor.data.Count; i++)
{
testDividend.data.Insert(0, this.data[dividendPosition--]);
}
if (testDividend < divisor)
{
testDividend.data.Insert(0, this.data[dividendPosition--]);
}
int numberOfPlacesAddedToLastTestDividend = 0;
do
{
int adjusterLength = testDividend.data.Count - divisor.data.Count + 1;
QuotienScratchAdjuster adjuster = new LargeInteger
{
data = new List<uint>(adjusterLength)
};
for (int i = 0; i < adjusterLength; i++)
{
((LargeInteger)adjuster).data.Add(0);
}
((LargeInteger)adjuster).data.Add(1);
LargeInteger quotientScratch = ((LargeInteger)adjuster).Clone();
LargeInteger compareDividend;
do
{
compareDividend = quotientScratch * divisor;
if (compareDividend > testDividend)
{
if (adjuster == 1)
{
quotientScratch--;
compareDividend -= divisor;
if (compareDividend < testDividend)
{
break;
}
}
else
{
adjuster.Halve();
quotientScratch -= adjuster;
}
}
else if (compareDividend < testDividend)
{
if (adjuster == 1)
{
LargeInteger tempCompareDividend = compareDividend;
compareDividend += divisor;
if (compareDividend > testDividend)
{
compareDividend = tempCompareDividend;
break;
}
quotientScratch++;
}
else
{
adjuster.Halve();
quotientScratch += adjuster;
}
}
else
{
break;
}
} while (true);
if (numberOfPlacesAddedToLastTestDividend > quotientScratch.data.Count)
{
if (numberOfPlacesAddedToLastTestDividend + 1 != quotientScratch.data.Count)
{
throw new ApplicationException(
$"Internal error: numberOfPlacesAddedToLastTestDividend > quotientScratch.data.Count && numberOfPlacesAddedToLastTestDividend {numberOfPlacesAddedToLastTestDividend} + 1 != quotientScratch.data.Count {quotientScratch.data.Count}. \r\nDividend:\r\n{this.PrintLargeInteger()}\r\nDivisor:\r\n{divisor.PrintLargeInteger()}");
}
quotient.data.Insert(0, 0);
}
for (int i = quotientScratch.data.Count - 1; i >= 0; i--)
{
quotient.data.Insert(0, quotientScratch.data[i]);
}
testDividend -= compareDividend;
numberOfPlacesAddedToLastTestDividend = 0;
for (int i = 0; i < divisor.data.Count; i++)
{
if (dividendPosition < 0)
{
break;
}
testDividend.data.Insert(0, this.data[dividendPosition--]);
numberOfPlacesAddedToLastTestDividend++;
}
if (testDividend < divisor)
{
if (dividendPosition < 0)
{
LargeInteger.Logger.Debug($"Exiting Divide. quotient: {quotient.PrintLargeInteger()}, remainder: {testDividend.PrintLargeInteger()}");
return new Tuple<LargeInteger, LargeInteger>(quotient, testDividend);
}
testDividend.data.Insert(0, this.data[dividendPosition--]);
numberOfPlacesAddedToLastTestDividend++;
}
} while (true);
}