public static Expression F(this string str)
{
var s = str.Split('/');
var top = int.Parse(s.First());
var bot = int.Parse(s.Last());
return(BigRational.FromIntFraction(top, bot));
}
public static BigRational ToFraction(this double x, double error = 0.0000000001)
{
int num;
int den;
var n = (int)Math.Floor(x);
x -= n;
if (x < error)
{
num = n;
den = 1;
return(BigRational.FromIntFraction(num, den));
}
if (1 - error < x)
{
num = n + 1;
den = 1;
return(BigRational.FromIntFraction(num, den));
}
var lowerN = 0;
var lowerD = 1;
var upperN = 1;
var upperD = 1;
while (true)
{
var middleN = lowerN + upperN;
var middleD = lowerD + upperD;
if (middleD * (x + error) < middleN)
{
upperN = middleN;
upperD = middleD;
}
else if (middleN < (x - error) * middleD)
{
lowerN = middleN;
lowerD = middleD;
}
else
{
num = n * middleD + middleN;
den = middleD;
return(BigRational.FromIntFraction(num, den));
}
}
//BigRational frac;
//if(x % 1 == 0) // if whole number
// {
// frac = BigRational.FromIntFraction((int) x, 1);
//} else {
// double dTemp = x;
// int iMultiple = 1;
// string strTemp = x.ToString();
// while(strTemp.IndexOf("E") > 0) // if in the form like 12E-9
// {
// dTemp *= 10;
// iMultiple *= 10;
// strTemp = dTemp.ToString();
// }
// int i = 0;
// while(strTemp[i] != '.')
// i++;
// int iDigitsAfterDecimal = strTemp.Length - i - 1;
// while(iDigitsAfterDecimal > 0) {
// dTemp *= 10;
// iMultiple *= 10;
// iDigitsAfterDecimal--;
// }
// frac = BigRational.FromIntFraction((int) Math.Round(dTemp), iMultiple);
//}
//return frac;
}
