public FunctionDraw(FunctionOfOneVariableD func, double step = 0.001d)
{
m_func = func;
m_step = step;
//m_beginX = beginX;
//m_endX = endX;
}
public static double GetMaxByThree(FunctionOfOneVariableD function, double left, double right)
{
do
{
double yLeft = function(left);
double yRight = function(right);
double mid = (left + right) / 2;
double yMid = function(mid);
double midMid = (left + mid) / 2;
double yMidMid = function(midMid);
if (yMidMid < yMid)
{
left = midMid;
}
else
{
right = mid;
}
if (Math.Abs(left - right) < 0.001d)
{
return(left);
}
} while (true);
}
/// <summary>
/// 反函数
/// </summary>
/// <param name="function"></param>
/// <param name="endY"></param>
/// <param name="beginX"></param>
/// <param name="delta"></param>
/// <returns></returns>
public static double InvertFunc(FunctionOfOneVariableD function, double endY, double beginX, double delta = 0.0001d)
{
double t1 = beginX;
double t2;
// 牛顿切线法求解L(t1) = L(1.0) * percent;
// Xn+1 = Xn - (L(xn) - L(1.0) * percent / L'(xn))
do
{
t2 = t1 - (function(t1) - endY) / DerivativeD(function, t1);
if (Math.Abs(t1 - t2) < 0.000001)
{
break;
}
t1 = t2;
} while (true);
return(t2);
}
/// <summary>
/// 求导数
/// </summary>
/// <param name="x"></param>
/// <returns></returns>
// public static float Derivative(FunctionOfOneVariable function, float x, float delta = 0.0001f)
// {
// return (function(x + delta) - function(x)) / delta;
// }
public static double DerivativeD(FunctionOfOneVariableD function, double x, double delta = 0.0001d)
{
return((function(x + delta) - function(x)) / delta);
}