/// <summary>
/// Division (this = this / n2)
/// </summary>
/// <param name="n2">The number to divide this by</param>
public void Div(BigFloat n2)
{
if (SpecialValueDivTest(n2)) return;
if (mantissa.Precision.NumBits >= 8192)
{
BigFloat rcp = n2.Reciprocal();
Mul(rcp);
}
else
{
int shift = mantissa.DivAndShift(n2.mantissa);
exponent = exponent - (n2.exponent + shift);
}
}
/// <summary>
/// Calculates the odd reciprocals of the natural numbers (for atan series)
/// </summary>
/// <param name="numBits"></param>
/// <param name="terms"></param>
private static void CalculateReciprocals(int numBits, int terms)
{
int bits = numBits + 32;
PrecisionSpec extendedPres = new PrecisionSpec(bits, PrecisionSpec.BaseType.BIN);
PrecisionSpec normalPres = new PrecisionSpec(numBits, PrecisionSpec.BaseType.BIN);
System.Collections.Generic.List<BigFloat> list = new System.Collections.Generic.List<BigFloat>(terms);
for (int i = 0; i < terms; i++)
{
BigFloat term = new BigFloat(i*2 + 1, extendedPres);
list.Add(new BigFloat(term.Reciprocal(), normalPres));
}
reciprocals = list.ToArray();
}
/// <summary>
/// Constructs a BigFloat from a string
/// </summary>
/// <param name="value"></param>
/// <param name="mantissaPrec"></param>
public BigFloat(string value, PrecisionSpec mantissaPrec)
{
Init(mantissaPrec);
PrecisionSpec extendedPres = new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN);
BigFloat ten = new BigFloat(10, extendedPres);
BigFloat iPart = new BigFloat(extendedPres);
BigFloat fPart = new BigFloat(extendedPres);
BigFloat tenRCP = ten.Reciprocal();
if (value.Contains(System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NaNSymbol))
{
SetNaN();
return;
}
else if (value.Contains(System.Globalization.CultureInfo.CurrentCulture.NumberFormat.PositiveInfinitySymbol))
{
SetInfPlus();
return;
}
else if (value.Contains(System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NegativeInfinitySymbol))
{
SetInfMinus();
return;
}
string decimalpoint = System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator;
char[] digitChars = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ',', '.' };
//Read in the integer part up the the decimal point.
bool sign = false;
value = value.Trim();
int i = 0;
if (value.Length > i && value[i] == '-')
{
sign = true;
i++;
}
if (value.Length > i && value[i] == '+')
{
i++;
}
for ( ; i < value.Length; i++)
{
//break on decimal point
if (value[i] == decimalpoint[0]) break;
int digit = Array.IndexOf(digitChars, value[i]);
if (digit < 0) break;
//Ignore place separators (assumed either , or .)
if (digit > 9) continue;
if (i > 0) iPart.Mul(ten);
iPart.Add(new BigFloat(digit, extendedPres));
}
//If we've run out of characters, assign everything and return
if (i == value.Length)
{
iPart.mantissa.Sign = sign;
exponent = iPart.exponent;
if (mantissa.AssignHigh(iPart.mantissa)) exponent++;
return;
}
//Assign the characters after the decimal point to fPart
if (value[i] == '.' && i < value.Length - 1)
{
BigFloat RecipToUse = new BigFloat(tenRCP);
for (i++; i < value.Length; i++)
{
int digit = Array.IndexOf(digitChars, value[i]);
if (digit < 0) break;
BigFloat temp = new BigFloat(digit, extendedPres);
temp.Mul(RecipToUse);
RecipToUse.Mul(tenRCP);
fPart.Add(temp);
}
}
//If we're run out of characters, add fPart and iPart and return
if (i == value.Length)
{
iPart.Add(fPart);
iPart.mantissa.Sign = sign;
exponent = iPart.exponent;
if (mantissa.AssignHigh(iPart.mantissa)) exponent++;
return;
}
if (value[i] == '+' || value[i] == '-') i++;
if (i == value.Length)
{
iPart.Add(fPart);
iPart.mantissa.Sign = sign;
exponent = iPart.exponent;
if (mantissa.AssignHigh(iPart.mantissa)) exponent++;
return;
}
//Look for exponential notation.
if ((value[i] == 'e' || value[i] == 'E') && i < value.Length - 1)
{
//Convert the exponent to an int.
int exp;
try
{
exp = System.Convert.ToInt32(new string(value.ToCharArray(i + 1, value.Length - (i + 1))));
}
catch (Exception)
{
iPart.Add(fPart);
iPart.mantissa.Sign = sign;
exponent = iPart.exponent;
if (mantissa.AssignHigh(iPart.mantissa)) exponent++;
return;
}
//Raise or lower 10 to the power of the exponent
BigFloat acc = new BigFloat(1, extendedPres);
BigFloat temp = new BigFloat(1, extendedPres);
int powerTemp = exp;
BigFloat multiplierToUse;
if (exp < 0)
{
multiplierToUse = new BigFloat(tenRCP);
powerTemp = -exp;
}
else
{
multiplierToUse = new BigFloat(ten);
}
//Fast power function
while (powerTemp != 0)
{
temp.Mul(multiplierToUse);
multiplierToUse.Assign(temp);
if ((powerTemp & 1) != 0)
{
acc.Mul(temp);
}
powerTemp >>= 1;
}
iPart.Add(fPart);
iPart.Mul(acc);
iPart.mantissa.Sign = sign;
exponent = iPart.exponent;
if (mantissa.AssignHigh(iPart.mantissa)) exponent++;
return;
}
iPart.Add(fPart);
iPart.mantissa.Sign = sign;
exponent = iPart.exponent;
if (mantissa.AssignHigh(iPart.mantissa)) exponent++;
}
private static void CalculateEOnly(int numBits)
{
PrecisionSpec extendedPrecision = new PrecisionSpec(numBits + 1, PrecisionSpec.BaseType.BIN);
PrecisionSpec normalPrecision = new PrecisionSpec(numBits, PrecisionSpec.BaseType.BIN);
int iExponent = (int)(Math.Sqrt(numBits));
BigFloat factorial = new BigFloat(1, extendedPrecision);
BigFloat constant = new BigFloat(1, extendedPrecision);
constant.exponent -= iExponent;
BigFloat numerator = new BigFloat(constant);
BigFloat reciprocal;
//Calculate the 2^iExponent th root of e
BigFloat e = new BigFloat(1, extendedPrecision);
int i;
for (i = 1; i < Int32.MaxValue; i++)
{
BigFloat number = new BigFloat(i, extendedPrecision);
factorial.Mul(number);
reciprocal = factorial.Reciprocal();
reciprocal.Mul(numerator);
if (-reciprocal.exponent > numBits) break;
e.Add(reciprocal);
numerator.Mul(constant);
System.GC.Collect();
}
for (i = 0; i < iExponent; i++)
{
numerator.Assign(e);
e.Mul(numerator);
}
//Set the cached static values.
eCache = new BigFloat(e, normalPrecision);
eRCPCache = new BigFloat(e.Reciprocal(), normalPrecision);
}
/// <summary>
/// Uses the Gauss-Legendre formula for pi
/// Taken from http://en.wikipedia.org/wiki/Gauss%E2%80%93Legendre_algorithm
/// </summary>
/// <param name="numBits"></param>
private static void CalculatePi(int numBits)
{
int bits = numBits + 32;
//Precision extend taken out.
PrecisionSpec normalPres = new PrecisionSpec(numBits, PrecisionSpec.BaseType.BIN);
PrecisionSpec extendedPres = new PrecisionSpec(bits, PrecisionSpec.BaseType.BIN);
if (scratch.Precision.NumBits != bits)
{
scratch = new BigInt(extendedPres);
}
//a0 = 1
BigFloat an = new BigFloat(1, extendedPres);
//b0 = 1/sqrt(2)
BigFloat bn = new BigFloat(2, extendedPres);
bn.Sqrt();
bn.exponent--;
//to = 1/4
BigFloat tn = new BigFloat(1, extendedPres);
tn.exponent -= 2;
int pn = 0;
BigFloat anTemp = new BigFloat(extendedPres);
int iteration = 0;
int cutoffBits = numBits >> 5;
for (iteration = 0; ; iteration++)
{
//Save a(n)
anTemp.Assign(an);
//Calculate new an
an.Add(bn);
an.exponent--;
//Calculate new bn
bn.Mul(anTemp);
bn.Sqrt();
//Calculate new tn
anTemp.Sub(an);
anTemp.mantissa.SquareHiFast(scratch);
anTemp.exponent += anTemp.exponent + pn + 1 - anTemp.mantissa.Normalise();
tn.Sub(anTemp);
anTemp.Assign(an);
anTemp.Sub(bn);
if (anTemp.exponent < -(bits - cutoffBits)) break;
//New pn
pn++;
}
an.Add(bn);
an.mantissa.SquareHiFast(scratch);
an.exponent += an.exponent + 1 - an.mantissa.Normalise();
tn.exponent += 2;
an.Div(tn);
pi = new BigFloat(an, normalPres);
piBy2 = new BigFloat(pi);
piBy2.exponent--;
twoPi = new BigFloat(pi, normalPres);
twoPi.exponent++;
piRecip = new BigFloat(an.Reciprocal(), normalPres);
twoPiRecip = new BigFloat(piRecip);
twoPiRecip.exponent--;
//1/3 is going to be useful for sin.
threeRecip = new BigFloat((new BigFloat(3, extendedPres)).Reciprocal(), normalPres);
}
private static void CalculateFactorials(int numBits)
{
System.Collections.Generic.List<BigFloat> list = new System.Collections.Generic.List<BigFloat>(64);
System.Collections.Generic.List<BigFloat> list2 = new System.Collections.Generic.List<BigFloat>(64);
PrecisionSpec extendedPrecision = new PrecisionSpec(numBits + 1, PrecisionSpec.BaseType.BIN);
PrecisionSpec normalPrecision = new PrecisionSpec(numBits, PrecisionSpec.BaseType.BIN);
BigFloat factorial = new BigFloat(1, extendedPrecision);
BigFloat reciprocal;
//Calculate e while we're at it
BigFloat e = new BigFloat(1, extendedPrecision);
list.Add(new BigFloat(factorial, normalPrecision));
for (int i = 1; i < Int32.MaxValue; i++)
{
BigFloat number = new BigFloat(i, extendedPrecision);
factorial.Mul(number);
if (factorial.exponent > numBits) break;
list2.Add(new BigFloat(factorial, normalPrecision));
reciprocal = factorial.Reciprocal();
e.Add(reciprocal);
list.Add(new BigFloat(reciprocal, normalPrecision));
}
//Set the cached static values.
inverseFactorialCache = list.ToArray();
factorialCache = list2.ToArray();
invFactorialCutoff = numBits;
eCache = new BigFloat(e, normalPrecision);
eRCPCache = new BigFloat(e.Reciprocal(), normalPrecision);
}
private static BigFloat R(BigFloat a0, BigFloat b0)
{
//Precision extend taken out.
int bits = a0.mantissa.Precision.NumBits;
PrecisionSpec extendedPres = new PrecisionSpec(bits, PrecisionSpec.BaseType.BIN);
BigFloat an = new BigFloat(a0, extendedPres);
BigFloat bn = new BigFloat(b0, extendedPres);
BigFloat sum = new BigFloat(extendedPres);
BigFloat term = new BigFloat(extendedPres);
BigFloat temp1 = new BigFloat(extendedPres);
BigFloat one = new BigFloat(1, extendedPres);
int iteration = 0;
for (iteration = 0; ; iteration++)
{
//Get the sum term for this iteration.
term.Assign(an);
term.Mul(an);
temp1.Assign(bn);
temp1.Mul(bn);
//term = an^2 - bn^2
term.Sub(temp1);
//term = 2^(n-1) * (an^2 - bn^2)
term.exponent += iteration - 1;
sum.Add(term);
if (term.exponent < -(bits - 8)) break;
//Calculate the new AGM estimates.
temp1.Assign(an);
an.Add(bn);
//a(n+1) = (an + bn) / 2
an.MulPow2(-1);
//b(n+1) = sqrt(an*bn)
bn.Mul(temp1);
bn.Sqrt();
}
one.Sub(sum);
one = one.Reciprocal();
return new BigFloat(one, a0.mantissa.Precision);
}
private static BigFloat TenPow(int power, PrecisionSpec precision)
{
BigFloat acc = new BigFloat(1, precision);
BigFloat temp = new BigFloat(1, precision);
int powerTemp = power;
BigFloat multiplierToUse = new BigFloat(10, precision);
if (power < 0)
{
multiplierToUse = multiplierToUse.Reciprocal();
powerTemp = -power;
}
//Fast power function
while (powerTemp != 0)
{
temp.Mul(multiplierToUse);
multiplierToUse.Assign(temp);
if ((powerTemp & 1) != 0)
{
acc.Mul(temp);
}
powerTemp >>= 1;
}
return acc;
}
/// <summary>
/// Calculates ln(2) and returns -10^(n/2 + a bit) for reuse, using the AGM method as described in
/// http://lacim.uqam.ca/~plouffe/articles/log2.pdf
/// </summary>
/// <param name="numBits"></param>
/// <returns></returns>
private static void CalculateLog2(int numBits)
{
//Use the AGM method formula to get log2 to N digits.
//R(a0, b0) = 1 / (1 - Sum(2^-n*(an^2 - bn^2)))
//log(1/2) = R(1, 10^-n) - R(1, 10^-n/2)
PrecisionSpec normalPres = new PrecisionSpec(numBits, PrecisionSpec.BaseType.BIN);
PrecisionSpec extendedPres = new PrecisionSpec(numBits + 1, PrecisionSpec.BaseType.BIN);
BigFloat a0 = new BigFloat(1, extendedPres);
BigFloat b0 = TenPow(-(int)((double)((numBits >> 1) + 2) * 0.302), extendedPres);
BigFloat pow10saved = new BigFloat(b0);
BigFloat firstAGMcacheSaved = new BigFloat(extendedPres);
//save power of 10 (in normal precision)
pow10cache = new BigFloat(b0, normalPres);
ln2cache = R(a0, b0);
//save the first half of the log calculation
firstAGMcache = new BigFloat(ln2cache, normalPres);
firstAGMcacheSaved.Assign(ln2cache);
b0.MulPow2(-1);
ln2cache.Sub(R(a0, b0));
//Convert to log(2)
ln2cache.mantissa.Sign = false;
//Save magic constant for newton log
//First guess in range 1 <= x < 2 is x0 = ln2 * (x - 1) + C
logNewtonConstant = new BigFloat(ln2cache);
logNewtonConstant.Mul(new BigFloat(3, extendedPres));
logNewtonConstant.exponent--;
logNewtonConstant.Sub(new BigFloat(1, extendedPres));
logNewtonConstant = new BigFloat(logNewtonConstant, normalPres);
//Save the inverse.
log2ecache = new BigFloat(ln2cache);
log2ecache = new BigFloat(log2ecache.Reciprocal(), normalPres);
//Now cache log10
//Because the log functions call this function to the precision to which they
//are called, we cannot call them without causing an infinite loop, so we need
//to inline the code.
log10recip = new BigFloat(10, extendedPres);
{
int power2 = log10recip.exponent + 1;
log10recip.exponent = -1;
//BigFloat res = new BigFloat(firstAGMcache);
BigFloat ax = new BigFloat(1, extendedPres);
BigFloat bx = new BigFloat(pow10saved);
bx.Mul(log10recip);
BigFloat r = R(ax, bx);
log10recip.Assign(firstAGMcacheSaved);
log10recip.Sub(r);
ax.Assign(ln2cache);
ax.Mul(new BigFloat(power2, log10recip.mantissa.Precision));
log10recip.Add(ax);
}
log10recip = log10recip.Reciprocal();
log10recip = new BigFloat(log10recip, normalPres);
//Trim to n bits
ln2cache = new BigFloat(ln2cache, normalPres);
}
/// <summary>
/// Returns a base-10 string representing the number.
///
/// Note: This is inefficient and possibly inaccurate. Please use with enough
/// rounding digits (set using the RoundingDigits property) to ensure accuracy
/// </summary>
public override string ToString()
{
if (IsSpecialValue)
{
SpecialValueType s = SpecialValue;
if (s == SpecialValueType.ZERO)
{
return String.Format("0{0}0", System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator);
}
else if (s == SpecialValueType.INF_PLUS)
{
return System.Globalization.CultureInfo.CurrentCulture.NumberFormat.PositiveInfinitySymbol;
}
else if (s == SpecialValueType.INF_MINUS)
{
return System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NegativeInfinitySymbol;
}
else if (s == SpecialValueType.NAN)
{
return System.Globalization.CultureInfo.CurrentCulture.NumberFormat.NaNSymbol;
}
else
{
return "Unrecognised special type";
}
}
if (scratch.Precision.NumBits != mantissa.Precision.NumBits)
{
scratch = new BigInt(mantissa.Precision);
}
//The mantissa expresses 1.xxxxxxxxxxx
//The highest possible value for the mantissa without the implicit 1. is 0.9999999...
scratch.Assign(mantissa);
//scratch.Round(3);
scratch.Sign = false;
BigInt denom = new BigInt("0", mantissa.Precision);
denom.SetBit(mantissa.Precision.NumBits - 1);
bool useExponentialNotation = false;
int halfBits = mantissa.Precision.NumBits / 2;
if (halfBits > 60) halfBits = 60;
int precDec = 10;
if (exponent > 0)
{
if (exponent < halfBits)
{
denom.RSH(exponent);
}
else
{
useExponentialNotation = true;
}
}
else if (exponent < 0)
{
int shift = -(exponent);
if (shift < precDec)
{
scratch.RSH(shift);
}
else
{
useExponentialNotation = true;
}
}
string output;
if (useExponentialNotation)
{
int absExponent = exponent;
if (absExponent < 0) absExponent = -absExponent;
int powerOf10 = (int)((double)absExponent * Math.Log10(2.0));
//Use 1 extra digit of precision (this is actually 32 bits more, nb)
BigFloat thisFloat = new BigFloat(this, new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN));
thisFloat.mantissa.Sign = false;
//Multiplicative correction factor to bring number into range.
BigFloat one = new BigFloat(1, new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN));
BigFloat ten = new BigFloat(10, new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN));
BigFloat tenRCP = ten.Reciprocal();
//Accumulator for the power of 10 calculation.
BigFloat acc = new BigFloat(1, new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN));
BigFloat tenToUse;
if (exponent > 0)
{
tenToUse = new BigFloat(tenRCP, new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN));
}
else
{
tenToUse = new BigFloat(ten, new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN));
}
BigFloat tenToPower = new BigFloat(1, new PrecisionSpec(mantissa.Precision.NumBits + 1, PrecisionSpec.BaseType.BIN));
int powerTemp = powerOf10;
//Fast power function
while (powerTemp != 0)
{
tenToPower.Mul(tenToUse);
tenToUse.Assign(tenToPower);
if ((powerTemp & 1) != 0)
{
acc.Mul(tenToPower);
}
powerTemp >>= 1;
}
thisFloat.Mul(acc);
//If we are out of range, correct.
if (thisFloat.GreaterThan(ten))
{
thisFloat.Mul(tenRCP);
if (exponent > 0)
{
powerOf10++;
}
else
{
powerOf10--;
}
}
else if (thisFloat.LessThan(one))
{
thisFloat.Mul(ten);
if (exponent > 0)
{
powerOf10--;
}
else
{
powerOf10++;
}
}
//Restore the precision and the sign.
BigFloat printable = new BigFloat(thisFloat, mantissa.Precision);
printable.mantissa.Sign = mantissa.Sign;
output = printable.ToString();
if (exponent < 0) powerOf10 = -powerOf10;
output = String.Format("{0}E{1}", output, powerOf10);
}
else
{
BigInt bigDigit = BigInt.Div(scratch, denom);
bigDigit.Sign = false;
scratch.Sub(BigInt.Mul(denom, bigDigit));
if (mantissa.Sign)
{
output = String.Format("-{0}.", bigDigit);
}
else
{
output = String.Format("{0}.", bigDigit);
}
denom = BigInt.Div(denom, 10u);
while (!denom.IsZero())
{
uint digit = (uint)BigInt.Div(scratch, denom);
if (digit == 10) digit--;
scratch.Sub(BigInt.Mul(denom, digit));
output = String.Format("{0}{1}", output, digit);
denom = BigInt.Div(denom, 10u);
}
output = RoundString(output, RoundingDigits);
}
return output;
}
