/// <summary>
/// フィルタの零点/極を計算。
/// 結果格納用の配列を関数内で確保。
/// </summary>
/// <returns>フィルタの零点/極一覧</returns>
public virtual ZeroPole[] GetZeroPole()
{
ZeroPole[] roots = new ZeroPole[this.Length];
for(int i=0; i<roots.Length; ++i) roots[i] = new ZeroPole();
this.GetZeroPole(roots);
return roots;
}
/// <summary>
/// フィルタの零点/極を計算。
/// 結果格納用の配列を関数内で確保。
/// </summary>
/// <returns>フィルタの零点/極一覧</returns>
public virtual ZeroPole[] GetZeroPole()
{
ZeroPole[] roots = new ZeroPole[this.Length];
for (int i = 0; i < roots.Length; ++i)
{
roots[i] = new ZeroPole();
}
this.GetZeroPole(roots);
return(roots);
}
/// <summary>
/// フィルタの零点/極を計算。
/// </summary>
/// <param name="roots">零点/極一覧の格納先</param>
public override void GetZeroPole(ZeroPole[] roots)
{
double m1 = this.m1;
double m1p = 1 - this.m1;
double Kk1 = Elliptic.K(m1);
double Kk1p = Elliptic.K(m1p);
double temp1 = -Math.PI * Kk1p / (this.order * Kk1);
double temp2 = Math.Exp(temp1);
double m = Elliptic.InverseQ(Math.Exp(-Math.PI * Kk1p / (this.order * Kk1)));
double mp = 1 - m;
double k = Math.Sqrt(m);
double Kk = Elliptic.K(m);
double Kkp = Elliptic.K(mp);
double temp3 = (Kk / Kkp) / (Kk1 / Kk1p);
double phi, sn_p, cn_p, dn_p;
double v = Elliptic.F(Math.Atan(1 / this.epsilon), m1p) * Kk / (this.order * Kk1);
Elliptic.Jacobi(v, mp, out phi, out sn_p, out cn_p, out dn_p);
for(int i=this.order-1, j=0; i>0; i-=2, ++j)
{
double sn, cn, dn;
double u = Kk * (double)i / this.order;
Elliptic.Jacobi(u, m, out phi, out sn, out cn, out dn);
double denom = 1 - dn * dn * sn_p * sn_p;
double re = -cn * dn * sn_p * cn_p / denom;
double im = -sn * dn_p / denom;
roots[j].zero = new Root(Root.Type.Complex, 0, 1 / (k * sn));
roots[j].pole = new Root(Root.Type.Complex, re, im);
}
if((this.order & 1) == 1)
{
double denom = 1 - sn_p * sn_p;
double re = -sn_p * cn_p / denom;
roots[this.order / 2].zero = new Root(Root.Type.None, 0, 0);
roots[this.order / 2].pole = new Root(Root.Type.Single, re, 0);
}
}
/// <summary>
/// フィルタの零点/極を計算。
/// </summary>
/// <param name="roots">零点/極一覧の格納先</param>
public override void GetZeroPole(ZeroPole[] roots)
{
for(int i=this.order-1, j=0; i>0; i-=2, ++j)
{
double w = Math.PI / 2.0 * (double)i / this.order;
double sin, cos;
GetSinCos(w, out sin, out cos);
roots[j].zero = new Root(Root.Type.None, 0, 0);
roots[j].pole = new Root(Root.Type.Complex, -cos, -sin);
}
if((this.order & 1) == 1)
{
roots[this.order / 2].zero = new Root(Root.Type.None, 0, 0);
roots[this.order / 2].pole = new Root(Root.Type.Single, -1, 0);
}
}
public static void ZeroPoleToAnalogPrototype(ZeroPole zeropole, Coefficient coef)
{
RootToAnalogPrototype(zeropole.zero, coef.b);
RootToAnalogPrototype(zeropole.pole, coef.a);
}
/// <summary> /// フィルタの零点/極を計算。 /// </summary> /// <param name="roots">零点/極一覧の格納先</param> public abstract void GetZeroPole(ZeroPole[] roots);
public static void ZeroPoleToAnalogPrototype(ZeroPole[] roots, Coefficient[] coefs)
{
for(int i=0; i<roots.Length; ++i)
{
ZeroPoleToAnalogPrototype(roots[i], coefs[i]);
}
}
public static void ZeroPoleToAnalogPrototype(ZeroPole zeropole, Coefficient coef)
{
RootToAnalogPrototype(zeropole.zero, coef.b);
RootToAnalogPrototype(zeropole.pole, coef.a);
}