public BigInteger modPow(BigInteger exponent, BigInteger m)
{
if (m.sign <= 0)
{
throw new ArithmeticException("BigInteger: modulus not positive");
}
BigInteger _base = this;
if (m.isOne() | (exponent.sign > 0 & _base.sign == 0))
{
return(BigInteger.ZERO);
}
if (_base.sign == 0 && exponent.sign == 0)
{
return(BigInteger.ONE);
}
if (exponent.sign < 0)
{
_base = modInverse(m);
exponent = exponent.negate();
}
// From now on: (m > 0) and (exponent >= 0)
BigInteger res = (m.testBit(0)) ? Division.oddModPow(_base.abs(),
exponent, m) : Division.evenModPow(_base.abs(), exponent, m);
if ((_base.sign < 0) && exponent.testBit(0))
{
// -b^e mod m == ((-1 mod m) * (b^e mod m)) mod m
res = m.subtract(BigInteger.ONE).multiply(res).mod(m);
}
// else exponent is even, so base^exp is positive
return(res);
}
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()));
}
internal static String bigInteger2String(BigInteger val, int radix)
{
int sign = val.sign;
int numberLength = val.numberLength;
int[] digits = val.digits;
if (sign == 0) {
return "0"; //$NON-NLS-1$
}
if (numberLength == 1) {
int highDigit = digits[numberLength - 1];
long v = highDigit & 0xFFFFFFFFL;
if (sign < 0) {
v = -v;
}
return Convert.ToString(v, radix);
}
if ((radix == 10) || (radix < 0)
|| (radix > 26)) {
return val.ToString();
}
double bitsForRadixDigit;
bitsForRadixDigit = Math.Log(radix) / Math.Log(2);
int resLengthInChars = (int) (val.abs().bitLength() / bitsForRadixDigit + ((sign < 0) ? 1
: 0)) + 1;
char[] result = new char[resLengthInChars];
int currentChar = resLengthInChars;
int resDigit;
if (radix != 16) {
int[] temp = new int[numberLength];
Array.Copy(digits, 0, temp, 0, numberLength);
int tempLen = numberLength;
int charsPerInt = digitFitInInt[radix];
int i;
// get the maximal power of radix that fits in int
int bigRadix = bigRadices[radix - 2];
while (true) {
// divide the array of digits by bigRadix and convert remainders
// to characters collecting them in the char array
resDigit = Division.divideArrayByInt(temp, temp, tempLen,
bigRadix);
int previous = currentChar;
do {
result[--currentChar] = Convert.ToString(resDigit % radix, radix)[0];
} while (((resDigit /= radix) != 0) && (currentChar != 0));
int delta = charsPerInt - previous + currentChar;
for (i = 0; i < delta && currentChar > 0; i++) {
result[--currentChar] = '0';
}
for (i = tempLen - 1; (i > 0) && (temp[i] == 0); i--) {
;
}
tempLen = i + 1;
if ((tempLen == 1) && (temp[0] == 0)) { // the quotient is 0
break;
}
}
} else {
// radix == 16
for (int i = 0; i < numberLength; i++) {
for (int j = 0; (j < 8) && (currentChar > 0); j++) {
resDigit = digits[i] >> (j << 2) & 0xf;
result[--currentChar] = Convert.ToString(resDigit % radix, 16)[0];
}
}
}
while (result[currentChar] == '0') {
currentChar++;
}
if (sign == -1) {
result[--currentChar] = '-';
}
return new String(result, currentChar, resLengthInChars - currentChar);
}
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());
}
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);
}
internal static String bigInteger2String(BigInteger val, int radix)
{
int sign = val.sign;
int numberLength = val.numberLength;
int[] digits = val.digits;
if (sign == 0)
{
return("0"); //$NON-NLS-1$
}
if (numberLength == 1)
{
int highDigit = digits[numberLength - 1];
long v = highDigit & 0xFFFFFFFFL;
if (sign < 0)
{
v = -v;
}
return(Convert.ToString(v, radix));
}
if ((radix == 10) || (radix < 0) ||
(radix > 26))
{
return(val.ToString());
}
double bitsForRadixDigit;
bitsForRadixDigit = Math.Log(radix) / Math.Log(2);
int resLengthInChars = (int)(val.abs().bitLength() / bitsForRadixDigit + ((sign < 0) ? 1
: 0)) + 1;
char[] result = new char[resLengthInChars];
int currentChar = resLengthInChars;
int resDigit;
if (radix != 16)
{
int[] temp = new int[numberLength];
Array.Copy(digits, 0, temp, 0, numberLength);
int tempLen = numberLength;
int charsPerInt = digitFitInInt[radix];
int i;
// get the maximal power of radix that fits in int
int bigRadix = bigRadices[radix - 2];
while (true)
{
// divide the array of digits by bigRadix and convert remainders
// to characters collecting them in the char array
resDigit = Division.divideArrayByInt(temp, temp, tempLen,
bigRadix);
int previous = currentChar;
do
{
result[--currentChar] = Convert.ToString(resDigit % radix, radix)[0];
} while (((resDigit /= radix) != 0) && (currentChar != 0));
int delta = charsPerInt - previous + currentChar;
for (i = 0; i < delta && currentChar > 0; i++)
{
result[--currentChar] = '0';
}
for (i = tempLen - 1; (i > 0) && (temp[i] == 0); i--)
{
;
}
tempLen = i + 1;
if ((tempLen == 1) && (temp[0] == 0)) // the quotient is 0
{
break;
}
}
}
else
{
// radix == 16
for (int i = 0; i < numberLength; i++)
{
for (int j = 0; (j < 8) && (currentChar > 0); j++)
{
resDigit = digits[i] >> (j << 2) & 0xf;
result[--currentChar] = Convert.ToString(resDigit % radix, 16)[0];
}
}
}
while (result[currentChar] == '0')
{
currentChar++;
}
if (sign == -1)
{
result[--currentChar] = '-';
}
return(new String(result, currentChar, resLengthInChars - currentChar));
}
