/// <summary>
/// 加法，有效位数取决于绝对误差最大的数
/// <para>例：1.001+100.1=101.1</para>
/// </summary>
/// <param name="a"></param>
/// <param name="b"></param>
/// <returns></returns>
public static SKSpecialDecimal operator +(SKSpecialDecimal a, SKSpecialDecimal b)
{
if (a.is_zero())
{
return(new SKSpecialDecimal(b));
}
else if (b.is_zero())
{
return(new SKSpecialDecimal(a));
}
SKSpecialDecimal a_copy = new SKSpecialDecimal(a);
SKSpecialDecimal b_copy = new SKSpecialDecimal(b);
//越小越精确，表示末位所在的位置
SKSpecialDecimal ret = add(a_copy, b_copy);
if (CUT_IN_OPERATOR)
{
int a_min_bit = a_copy.exp_10 - a_copy.get_digit() + 1;
int b_min_bit = b_copy.exp_10 - b_copy.get_digit() + 1;
int ret_min_bit = ret.exp_10 - ret.get_digit() + 1;
if (a_min_bit > b_min_bit)//以a的精度为准
{
ret.cut(ret.get_digit() - a_min_bit + ret_min_bit);
}
else//以b的精度为准
{
ret.cut(ret.get_digit() - b_min_bit + ret_min_bit);
}
}
return(ret);
}
/// <summary>
/// 除法，结果的有效位数与两数有效位数较少的数相同
/// </summary>
/// <param name="a">除数</param>
/// <param name="b">被除数</param>
/// <returns></returns>
public static SKSpecialDecimal operator /(SKSpecialDecimal a, SKSpecialDecimal b)
{
if (a.get_digit() == 0 || b.get_digit() == 0)
{
return(new SKSpecialDecimal());
}
int less = Math.Min(a.get_digit(), b.get_digit());
SKSpecialDecimal ret = div(a, b);
if (CUT_IN_OPERATOR)
{
ret.cut(less);
}
return(ret);
}
/// <summary>
/// 在(x-1)位处发生进位，同时截取x位有效数字
/// </summary>
/// <param name="x"></param>
private void upgrade(int x)
{
if (x < 2)
{
return;
}
data.RemoveRange(x, data.Count - x);
SKSpecialDecimal _tmp = new SKSpecialDecimal(this);
SKSpecialDecimal _add = new SKSpecialDecimal();
_add[x - 1] = 1;
_add.exp_10 = _tmp.get_exp();
_tmp = add(_tmp, _add);
if (_tmp.get_digit() > get_digit()) //进位导致位数增加了
{
_tmp.cut(get_digit()); //本次cut一定不会导致进位了
}
reset(_tmp);
}
