本文整理汇总了C#中BigDecimal.Round方法的典型用法代码示例。如果您正苦于以下问题:C# BigDecimal.Round方法的具体用法?C# BigDecimal.Round怎么用?C# BigDecimal.Round使用的例子?那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类BigDecimal
的用法示例。
在下文中一共展示了BigDecimal.Round方法的3个代码示例,这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞,您的评价将有助于系统推荐出更棒的C#代码示例。
示例1: PowRound
public static BigDecimal PowRound(BigDecimal x, Rational q)
{
/** Special cases: x^1=x and x^0 = 1
*/
if (q.CompareTo(BigInteger.One) == 0)
return x;
if (q.Sign == 0)
return BigDecimal.One;
if (q.IsInteger) {
/* We are sure that the denominator is positive here, because normalize() has been
* called during constrution etc.
*/
return PowRound(x, q.Numerator);
}
/* Refuse to operate on the general negative basis. The integer q have already been handled above.
*/
if (x.CompareTo(BigDecimal.Zero) < 0)
throw new ArithmeticException("Cannot power negative " + x);
if (q.IsIntegerFraction) {
/* Newton method with first estimate in double precision.
* The disadvantage of this first line here is that the result must fit in the
* standard range of double precision numbers exponents.
*/
double estim = System.Math.Pow(x.ToDouble(), q.ToDouble());
var res = new BigDecimal(estim);
/* The error in x^q is q*x^(q-1)*Delta(x).
* The relative error is q*Delta(x)/x, q times the relative error of x.
*/
var reserr = new BigDecimal(0.5*q.Abs().ToDouble()
*x.Ulp().Divide(x.Abs(), MathContext.Decimal64).ToDouble());
/* The main point in branching the cases above is that this conversion
* will succeed for numerator and denominator of q.
*/
int qa = q.Numerator.ToInt32();
int qb = q.Denominator.ToInt32();
/* Newton iterations. */
BigDecimal xpowa = PowRound(x, qa);
for (;;) {
/* numerator and denominator of the Newton term. The major
* disadvantage of this implementation is that the updates of the powers
* of the new estimate are done in full precision calling BigDecimal.pow(),
* which becomes slow if the denominator of q is large.
*/
BigDecimal nu = res.Pow(qb).Subtract(xpowa);
BigDecimal de = MultiplyRound(res.Pow(qb - 1), q.Denominator);
/* estimated correction */
BigDecimal eps = nu.Divide(de, MathContext.Decimal64);
BigDecimal err = res.Multiply(reserr, MathContext.Decimal64);
int precDiv = 2 + ErrorToPrecision(eps, err);
if (precDiv <= 0) {
/* The case when the precision is already reached and any precision
* will do. */
eps = nu.Divide(de, MathContext.Decimal32);
} else {
eps = nu.Divide(de, new MathContext(precDiv));
}
res = SubtractRound(res, eps);
/* reached final precision if the relative error fell below reserr,
* |eps/res| < reserr
*/
if (eps.Divide(res, MathContext.Decimal64).Abs().CompareTo(reserr) < 0) {
/* delete the bits of extra precision kept in this
* working copy.
*/
return res.Round(new MathContext(ErrorToPrecision(reserr.ToDouble())));
}
}
}
/* The error in x^q is q*x^(q-1)*Delta(x) + Delta(q)*x^q*log(x).
* The relative error is q/x*Delta(x) + Delta(q)*log(x). Convert q to a floating point
* number such that its relative error becomes negligible: Delta(q)/q << Delta(x)/x/log(x) .
*/
int precq = 3 + ErrorToPrecision((x.Ulp().Divide(x, MathContext.Decimal64)).ToDouble()
/System.Math.Log(x.ToDouble()));
/* Perform the actual calculation as exponentiation of two floating point numbers.
*/
return Pow(x, q.ToBigDecimal(new MathContext(precq)));
}
示例2: Root
public static BigDecimal Root(int n, BigDecimal x)
{
if (x.CompareTo(BigDecimal.Zero) < 0)
throw new ArithmeticException("negative argument " + x + " of root");
if (n <= 0)
throw new ArithmeticException("negative power " + n + " of root");
if (n == 1)
return x;
/* start the computation from a double precision estimate */
var s = new BigDecimal(System.Math.Pow(x.ToDouble(), 1.0/n));
/* this creates nth with nominal precision of 1 digit
*/
var nth = new BigDecimal(n);
/* Specify an internal accuracy within the loop which is
* slightly larger than what is demanded by 'eps' below.
*/
BigDecimal xhighpr = ScalePrecision(x, 2);
var mc = new MathContext(2 + x.Precision);
/* Relative accuracy of the result is eps.
*/
double eps = x.Ulp().ToDouble()/(2*n*x.ToDouble());
for (;;) {
/* s = s -(s/n-x/n/s^(n-1)) = s-(s-x/s^(n-1))/n; test correction s/n-x/s for being
* smaller than the precision requested. The relative correction is (1-x/s^n)/n,
*/
BigDecimal c = xhighpr.Divide(s.Pow(n - 1), mc);
c = s.Subtract(c);
var locmc = new MathContext(c.Precision);
c = c.Divide(nth, locmc);
s = s.Subtract(c);
if (System.Math.Abs(c.ToDouble()/s.ToDouble()) < eps)
break;
}
return s.Round(new MathContext(ErrorToPrecision(eps)));
}
示例3: RoundMathContextPrecision0
public void RoundMathContextPrecision0()
{
String a = "3736186567876876578956958765675671119238118911893939591735";
int aScale = 45;
int precision = 0;
RoundingMode rm = RoundingMode.HalfUp;
MathContext mc = new MathContext(precision, rm);
String res = "3736186567876.876578956958765675671119238118911893939591735";
BigDecimal aNumber = new BigDecimal(BigInteger.Parse(a), aScale);
BigDecimal result = aNumber.Round(mc);
Assert.AreEqual(res, result.ToString(), "incorrect quotient value");
Assert.AreEqual(aScale, result.Scale, "incorrect quotient scale");
}