有没有在C＃中BigFloat类？ [英] Is there a BigFloat class in C#?
问题描述
System.Numerics.BigInteger 让你乘大整数在一起，但有相同类型的浮点数的东西吗？如果没有，有没有免费的图书馆，我可以使用？
//这个但花车
System.Numerics.BigInteger MAXINT =新的BigInteger（int.MaxValue）;System.Numerics.BigInteger大= MAXINT * MAXINT * MAXINT;
的System.Console.WriteLine（大）;
也许你正在寻找的 BigRational ？微软发布它codePLEX他们BCL项目中。实际上并不知道如何或是否会满足您的需求。
它保持它作为一个理性的数字。你可以得到一个字符串的十进制值或者通过铸造或某些乘法。
变种R =新BigRational（5000，3768）;
Console.WriteLine（（十进制）R）;
Console.WriteLine（（双）R）;
或者用一个简单的（ISH）扩展这样的方式：
公共静态类BigRationalExtensions
{
公共静态字符串ToDecimalString（这BigRational R，INT precision）
{
变种分数= r.GetFractionPart（）; //案例其中有理数是一个整数
如果（fraction.Numerator == 0安培;＆安培; fraction.Denominator == 1）
{
返回r.GetWholePart（）+.0;
} VAR adjustedNumerator =（fraction.Numerator
* BigInteger.Pow（10，precision））;
VAR小数位数= adjustedNumerator / fraction.Denominator; //情况precision是不是足够大。
如果（小数位数== 0）
{
回到0.0;
} //给它周边的我们应该需要什么能力
//整数部分和总precision
//（这是有点草率，但确实的伎俩）
VAR SB =新的StringBuilder（precision + r.ToString（）长。）; 布尔noMoreTrailingZeros = FALSE;
的for（int i = precision; I＆GT; 0;我 - ）
{
如果（！noMoreTrailingZeros）
{
如果（（小数位数％10）== 0）
{
小数位数=小数位数/ 10;
继续;
} noMoreTrailingZeros = TRUE;
} //最右边的小数添加到字符串
sb.Insert（0，小数位数％10）;
小数位数=小数位数/ 10;
} //将整个零件和小数
sb.Insert（0，。）;
sb.Insert（0，r.GetWholePart（））; 返回sb.ToString（）;
}
}
如果它出了小数或双的precision范围，它们将被转换为各自类型的值0.0。此外，铸造为十进制，当结果是它的范围之外，将导致发生OverflowException 抛出。
扩展方法我写的（这可能不是的最的方法来计算分数的小数重presentation）将准确地将其转换为一个字符串，具有无限precision。然而，如果数目比所请求的precision较小，它将返回0.0，就像十进制或双会
System.Numerics.BigInteger lets you multiply large integers together, but is there anything of the same type for floating point numbers? If not, is there a free library I can use?
//this but with floats
System.Numerics.BigInteger maxint = new BigInteger(int.MaxValue);
System.Numerics.BigInteger big = maxint * maxint * maxint;
System.Console.WriteLine(big);
Perhaps you're looking for BigRational? Microsoft released it under their BCL project on CodePlex. Not actually sure how or if it will fit your needs.
It keeps it as a rational number. You can get the a string with the decimal value either by casting or some multiplication.
var r = new BigRational(5000, 3768);
Console.WriteLine((decimal)r);
Console.WriteLine((double)r);
Or with a simple(ish) extension method like this:
public static class BigRationalExtensions
{
public static string ToDecimalString(this BigRational r, int precision)
{
var fraction = r.GetFractionPart();
// Case where the rational number is a whole number
if(fraction.Numerator == 0 && fraction.Denominator == 1)
{
return r.GetWholePart() + ".0";
}
var adjustedNumerator = (fraction.Numerator
* BigInteger.Pow(10, precision));
var decimalPlaces = adjustedNumerator / fraction.Denominator;
// Case where precision wasn't large enough.
if(decimalPlaces == 0)
{
return "0.0";
}
// Give it the capacity for around what we should need for
// the whole part and total precision
// (this is kinda sloppy, but does the trick)
var sb = new StringBuilder(precision + r.ToString().Length);
bool noMoreTrailingZeros = false;
for (int i = precision; i > 0; i--)
{
if(!noMoreTrailingZeros)
{
if ((decimalPlaces%10) == 0)
{
decimalPlaces = decimalPlaces/10;
continue;
}
noMoreTrailingZeros = true;
}
// Add the right most decimal to the string
sb.Insert(0, decimalPlaces%10);
decimalPlaces = decimalPlaces/10;
}
// Insert the whole part and decimal
sb.Insert(0, ".");
sb.Insert(0, r.GetWholePart());
return sb.ToString();
}
}
If it's out of the precision range of a decimal or double, they will be cast to their respective types with a value of 0.0. Also, casting to decimal, when the result is outside of its range, will cause an OverflowException to be thrown.
The extension method I wrote (which may not be the best way to calculate a fraction's decimal representation) will accurately convert it to a string, with unlimited precision. However, if the number is smaller than the precision requested, it will return 0.0, just like decimal or double would.
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