private void TestDiv(BigInteger i1, BigInteger i2)
{
BigInteger q = i1 / i2;
BigInteger r = BigMath.Remainder(i1, i2);
BigInteger remainder;
BigInteger quotient = BigMath.DivideAndRemainder(i1, i2, out remainder);
Assert.True(q.Equals(quotient), "Divide and DivideAndRemainder do not agree");
Assert.True(r.Equals(remainder), "Remainder and DivideAndRemainder do not agree");
Assert.True(q.Sign != 0 || q.Equals(zero), "signum and equals(zero) do not agree on quotient");
Assert.True(r.Sign != 0 || r.Equals(zero), "signum and equals(zero) do not agree on remainder");
Assert.True(q.Sign == 0 || q.Sign == i1.Sign * i2.Sign, "wrong sign on quotient");
Assert.True(r.Sign == 0 || r.Sign == i1.Sign, "wrong sign on remainder");
Assert.True(BigMath.Abs(r).CompareTo(BigMath.Abs(i2)) < 0, "remainder out of range");
Assert.True(((BigMath.Abs(q) + one) * BigMath.Abs(i2)).CompareTo(BigMath.Abs(i1)) > 0, "quotient too small");
Assert.True((BigMath.Abs(q) * BigMath.Abs(i2)).CompareTo(BigMath.Abs(i1)) <= 0, "quotient too large");
BigInteger p = q * i2;
BigInteger a = p + r;
Assert.True(a.Equals(i1), "(a/b)*b+(a%b) != a");
try {
BigInteger mod = i1 % i2;
Assert.True(mod.Sign >= 0, "mod is negative");
Assert.True(BigMath.Abs(mod).CompareTo(BigMath.Abs(i2)) < 0, "mod out of range");
Assert.True(r.Sign < 0 || r.Equals(mod), "positive remainder == mod");
Assert.True(r.Sign >= 0 || r.Equals(mod - i2), "negative remainder == mod - divisor");
} catch (ArithmeticException e) {
Assert.True(i2.Sign <= 0, "mod fails on negative divisor only");
}
}
public void RemainderBigInteger()
{
Assert.Throws <ArithmeticException>(() => BigMath.Remainder(largePos, zero));
Assert.Throws <ArithmeticException>(() => BigMath.Remainder(bi1, zero));
Assert.Throws <ArithmeticException>(() => BigMath.Remainder(-bi3, zero));
Assert.Throws <ArithmeticException>(() => BigMath.Remainder(zero, zero));
}
// TODO: must be verified
public decimal ToDecimal()
{
var scaleDivisor = BigMath.Pow(BigInteger.FromInt64(10), _scale);
var remainder = BigMath.Remainder(GetUnscaledValue(), scaleDivisor);
var scaledValue = GetUnscaledValue() / scaleDivisor;
var leftOfDecimal = (decimal)scaledValue;
var rightOfDecimal = (remainder) / ((decimal)scaleDivisor);
return(leftOfDecimal + rightOfDecimal);
}
public static BigInteger Mod(BigInteger value, BigInteger m)
{
if (m.Sign <= 0)
{
// math.18=BigInteger: modulus not positive
throw new ArithmeticException(Messages.math18); //$NON-NLS-1$
}
BigInteger rem = BigMath.Remainder(value, m);
return((rem.Sign < 0) ? rem + m : rem);
}
/**
* @param m a positive modulus
* Return the greatest common divisor of op1 and op2,
*
* @param op1
* must be greater than zero
* @param op2
* must be greater than zero
* @see BigInteger#gcd(BigInteger)
* @return {@code GCD(op1, op2)}
*/
public 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.LowestSetBit;
int lsb2 = op2.LowestSetBit;
int pow2Count = System.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.FromInt64(Division.GcdBinary(op1.ToInt64(),
op2.ToInt64()));
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 = BigMath.Remainder(op2, op1);
if (op2.Sign != 0)
{
BitLevel.InplaceShiftRight(op2, op2.LowestSetBit);
}
}
else
{
// Use Knuth's algorithm of successive subtract and shifting
do
{
Elementary.inplaceSubtract(op2, op1); // both are odd
BitLevel.InplaceShiftRight(op2, op2.LowestSetBit); // op2 is even
} while (op2.CompareTo(op1) >= BigInteger.EQUALS);
}
// now op1 >= op2
swap = op2;
op2 = op1;
op1 = swap;
} while (op1.Sign != 0);
return(op2 << pow2Count);
}