/// <summary>
/// 自然対数の底の指数関数。マクローリン展開の収束半径が∞であることを利用。
/// </summary>
/// <param name="val">指数</param>
/// <returns></returns>
public double CreateNapierFunc(double val)
{
double Val = 0;
double buf = 0;
for (int ic = 0; ic < 1000; ic++)
{
buf += BinomialTheorem.RealExpo(val, ic) / BinomialTheorem.DoubleFactorial(ic);
}
Val = buf;
return(Val);
}
/// <summary>
/// 円周率を求める。
/// ラマヌジャンの公式を使用
/// </summary>
protected static void CreatePI()
{
double buf1 = 0;
double buf2 = 1;
int ic = 0;
while (buf1 != buf2)
{
buf2 = buf1;
buf1 += (BinomialTheorem.RealExpo(-1, ic) * BinomialTheorem.DoubleFactorial(4 * ic) * (1123 + 21460 * ic))
/ (BinomialTheorem.RealExpo(882, 2 * ic + 1) * BinomialTheorem.RealExpo(BinomialTheorem.RealExpo(4, ic) * BinomialTheorem.DoubleFactorial(ic), 4));
ic += 1;
}
PI = 4 / buf1;
}
/// <summary>
/// ラジアンを入力すると余弦の値を返す。0 <= rad < 2PI
/// </summary>
/// <param name="rad"></param>
/// <returns></returns>
public static double RadCosine(double rad)
{
double Cos = 0;
double buf = 0;
if (rad == PI / 2)
{
return(0);
}
if (rad == PI / 3)
{
return(0.5);
}
if (rad == 0)
{
return(1);
}
for (int ic = 0; ic < 100; ic++)
{
buf += BinomialTheorem.RealExpo(-1, ic) * BinomialTheorem.RealExpo(rad, 2 * ic) / BinomialTheorem.DoubleFactorial(2 * ic);
}
Cos = buf;
return(Cos);
}
/// <summary>
/// ラジアンを入力すると正弦の値を返す。0 <= rad < 2PI
/// </summary>
/// <param name="rad">ラジアン</param>
/// <returns></returns>
public static double RadSine(double rad)
{
double Sine = 0;
double buf = 0;
if (rad == PI / 2)
{
return(1);
}
if (rad == PI / 6)
{
return(0.5);
}
if (rad == 0)
{
return(0);
}
if (Math.Floor(rad % PI) == rad % PI)
{
return(0);
}
for (int ic = 0; ic < 100; ic++)
{
buf += BinomialTheorem.RealExpo(-1, ic) * BinomialTheorem.RealExpo(rad, 2 * ic + 1) / BinomialTheorem.DoubleFactorial(2 * ic + 1);
}
Sine = buf;
return(Sine);
}
