public static double?Limit(MonoFunctionHandler f, double precision, LimVariable point) //返回一个一元函数在某点的左右极限值
{
if (f == null)
{
throw new ArgumentNullException("Function Null");
}
double res = 0;
precision = Math.Abs(precision);
try
{
switch (point.Sign)
{
case LimSign.Negative:
res = f(point.Value - precision);
break;
case LimSign.Positive:
res = f(point.Value + precision);
break;
}
}
catch (Exception) //极限不存在或其他错误
{
//MessageBox
return(null);
}
return(res);
}
public static double?Derivative(MonoFunctionHandler f, LimVariable x, double precision = 1E-3) //返回一个一元函数在某点的左右导数值；precision过大会引入较大误差，precision过小会导致数值结果不稳定
{
if (f == null)
{
throw new ArgumentNullException("Function Null");
}
double res = 0;
precision = Math.Abs(precision);
try
{
switch (x.Sign)
{
case LimSign.Negative:
res = (-25 * f(x.Value) + 48 * f(x.Value - precision) - 36 * f(x.Value - 2 * precision) + 16 * f(x.Value - 3 * precision) - 3 * f(x.Value - 4 * precision)) / (12 * -precision); //五点公式
break;
case LimSign.Positive:
res = (-25 * f(x.Value) + 48 * f(x.Value + precision) - 36 * f(x.Value + 2 * precision) + 16 * f(x.Value + 3 * precision) - 3 * f(x.Value + 4 * precision)) / (12 * precision);
break;
}
}
catch (Exception) //导数不存在或其他错误
{
//MessageBox
return(null);
}
return(res);
}