public BigInteger gcd(BigInteger val)
{
BigInteger val1 = this.abs();
BigInteger val2 = val.abs();
// To avoid a possible division by zero
if (val1.signum() == 0)
{
return(val2);
}
else if (val2.signum() == 0)
{
return(val1);
}
// Optimization for small operands
// (op2.bitLength() < 64) and (op1.bitLength() < 64)
if (((val1.numberLength == 1) || ((val1.numberLength == 2) && (val1.digits[1] > 0))) &&
(val2.numberLength == 1 || (val2.numberLength == 2 && val2.digits[1] > 0)))
{
return(BigInteger.valueOf(Division.gcdBinary(val1.longValue(), val2
.longValue())));
}
return(Division.gcdBinary(val1.copy(), val2.copy()));
}
/** @see BigInteger#doubleValue() */
internal static double bigInteger2Double(BigInteger val)
{
// val.bitLength() < 64
if ((val.numberLength < 2)
|| ((val.numberLength == 2) && (val.digits[1] > 0))) {
return val.longValue();
}
// val.bitLength() >= 33 * 32 > 1024
if (val.numberLength > 32) {
return ((val.sign > 0) ? double.PositiveInfinity
: double.NegativeInfinity);
}
return Convert.ToDouble(val.ToString());
}
/** @see BigInteger#doubleValue() */
internal static double bigInteger2Double(BigInteger val)
{
// val.bitLength() < 64
if ((val.numberLength < 2) ||
((val.numberLength == 2) && (val.digits[1] > 0)))
{
return(val.longValue());
}
// val.bitLength() >= 33 * 32 > 1024
if (val.numberLength > 32)
{
return((val.sign > 0) ? double.PositiveInfinity
: double.NegativeInfinity);
}
return(Convert.ToDouble(val.ToString()));
}
internal static BigInteger gcdBinary(BigInteger op1, BigInteger op2)
{
// PRE: (op1 > 0) and (op2 > 0)
/*
* Divide both number the maximal possible times by 2 without rounding
* gcd(2*a, 2*b) = 2 * gcd(a,b)
*/
int lsb1 = op1.getLowestSetBit();
int lsb2 = op2.getLowestSetBit();
int pow2Count = Math.Min(lsb1, lsb2);
BitLevel.inplaceShiftRight(op1, lsb1);
BitLevel.inplaceShiftRight(op2, lsb2);
BigInteger swap;
// I want op2 > op1
if (op1.compareTo(op2) == BigInteger.GREATER) {
swap = op1;
op1 = op2;
op2 = swap;
}
do { // INV: op2 >= op1 && both are odd unless op1 = 0
// Optimization for small operands
// (op2.bitLength() < 64) implies by INV (op1.bitLength() < 64)
if (( op2.numberLength == 1 )
|| ( ( op2.numberLength == 2 ) && ( op2.digits[1] > 0 ) )) {
op2 = BigInteger.valueOf(Division.gcdBinary(op1.longValue(),
op2.longValue()));
break;
}
// Implements one step of the Euclidean algorithm
// To reduce one operand if it's much smaller than the other one
if (op2.numberLength > op1.numberLength * 1.2) {
op2 = op2.remainder(op1);
if (op2.signum() != 0) {
BitLevel.inplaceShiftRight(op2, op2.getLowestSetBit());
}
} else {
// Use Knuth's algorithm of successive subtract and shifting
do {
Elementary.inplaceSubtract(op2, op1); // both are odd
BitLevel.inplaceShiftRight(op2, op2.getLowestSetBit()); // op2 is even
} while (op2.compareTo(op1) >= BigInteger.EQUALS);
}
// now op1 >= op2
swap = op2;
op2 = op1;
op1 = swap;
} while (op1.sign != 0);
return op2.shiftLeft(pow2Count);
}
internal static BigInteger gcdBinary(BigInteger op1, BigInteger op2)
{
// PRE: (op1 > 0) and (op2 > 0)
/*
* Divide both number the maximal possible times by 2 without rounding
* gcd(2*a, 2*b) = 2 * gcd(a,b)
*/
int lsb1 = op1.getLowestSetBit();
int lsb2 = op2.getLowestSetBit();
int pow2Count = Math.Min(lsb1, lsb2);
BitLevel.inplaceShiftRight(op1, lsb1);
BitLevel.inplaceShiftRight(op2, lsb2);
BigInteger swap;
// I want op2 > op1
if (op1.compareTo(op2) == BigInteger.GREATER)
{
swap = op1;
op1 = op2;
op2 = swap;
}
do // INV: op2 >= op1 && both are odd unless op1 = 0
// Optimization for small operands
// (op2.bitLength() < 64) implies by INV (op1.bitLength() < 64)
{
if ((op2.numberLength == 1) ||
((op2.numberLength == 2) && (op2.digits[1] > 0)))
{
op2 = BigInteger.valueOf(Division.gcdBinary(op1.longValue(),
op2.longValue()));
break;
}
// Implements one step of the Euclidean algorithm
// To reduce one operand if it's much smaller than the other one
if (op2.numberLength > op1.numberLength * 1.2)
{
op2 = op2.remainder(op1);
if (op2.signum() != 0)
{
BitLevel.inplaceShiftRight(op2, op2.getLowestSetBit());
}
}
else
{
// Use Knuth's algorithm of successive subtract and shifting
do
{
Elementary.inplaceSubtract(op2, op1); // both are odd
BitLevel.inplaceShiftRight(op2, op2.getLowestSetBit()); // op2 is even
} while (op2.compareTo(op1) >= BigInteger.EQUALS);
}
// now op1 >= op2
swap = op2;
op2 = op1;
op1 = swap;
} while (op1.sign != 0);
return(op2.shiftLeft(pow2Count));
}
private void setUnscaledValue(BigInteger unscaledValue)
{
this.intVal = unscaledValue;
this._bitLength = unscaledValue.bitLength();
if(this._bitLength < 64) {
this.smallValue = unscaledValue.longValue();
}
}
private static BigDecimal divideBigIntegers(BigInteger scaledDividend, BigInteger scaledDivisor, int scale, RoundingMode roundingMode)
{
BigInteger[] quotAndRem = scaledDividend.divideAndRemainder(scaledDivisor); // quotient and remainder
// If after division there is a remainder...
BigInteger quotient = quotAndRem[0];
BigInteger remainder = quotAndRem[1];
if (remainder.signum() == 0) {
return new BigDecimal(quotient, scale);
}
int sign = scaledDividend.signum() * scaledDivisor.signum();
int compRem; // 'compare to remainder'
if(scaledDivisor.bitLength() < 63) { // 63 in order to avoid out of long after <<1
long rem = remainder.longValue();
long divisor = scaledDivisor.longValue();
compRem = longCompareTo(Math.Abs(rem) << 1,Math.Abs(divisor));
// To look if there is a carry
compRem = roundingBehavior(quotient.testBit(0) ? 1 : 0,
sign * (5 + compRem), roundingMode);
} else {
// Checking if: remainder * 2 >= scaledDivisor
compRem = remainder.abs().shiftLeftOneBit().compareTo(scaledDivisor.abs());
compRem = roundingBehavior(quotient.testBit(0) ? 1 : 0,
sign * (5 + compRem), roundingMode);
}
if (compRem != 0) {
if(quotient.bitLength() < 63) {
return valueOf(quotient.longValue() + compRem,scale);
}
quotient = quotient.add(BigInteger.valueOf(compRem));
return new BigDecimal(quotient, scale);
}
// Constructing the result with the appropriate unscaled value
return new BigDecimal(quotient, scale);
}
