PartialFractionDecomposition(
WWComplex [] nCoeffs, WWComplex [] dRoots)
{
var result = new List <FirstOrderComplexRationalPolynomial>();
if (dRoots.Length == 1 && nCoeffs.Length == 1)
{
result.Add(new FirstOrderComplexRationalPolynomial(WWComplex.Zero(),
nCoeffs[0], WWComplex.Unity(), WWComplex.Minus(dRoots[0])));
return(result);
}
if (dRoots.Length < 2)
{
throw new ArgumentException("denomR");
}
if (dRoots.Length < nCoeffs.Length)
{
throw new ArgumentException("nCoeffs");
}
for (int k = 0; k < dRoots.Length; ++k)
{
// cn = ... + nCoeffs[2]s^2 + nCoeffs[1]s + nCoeffs[0]
// 係数c[0]は、s==denomR[0]としたときの、cn/(s-denomR[1])(s-denomR[2])(s-denomR[3])…(s-denomR[p-1])
// 係数c[1]は、s==denomR[1]としたときの、cn/(s-denomR[0])(s-denomR[2])(s-denomR[3])…(s-denomR[p-1])
// 係数c[2]は、s==denomR[2]としたときの、cn/(s-denomR[0])(s-denomR[1])(s-denomR[3])…(s-denomR[p-1])
// 分子の値c。
var c = WWComplex.Zero();
var s = WWComplex.Unity();
for (int j = 0; j < nCoeffs.Length; ++j)
{
c = WWComplex.Add(c, WWComplex.Mul(nCoeffs[j], s));
s = WWComplex.Mul(s, dRoots[k]);
}
for (int i = 0; i < dRoots.Length; ++i)
{
if (i == k)
{
continue;
}
c = WWComplex.Div(c, WWComplex.Sub(dRoots[k], dRoots[i]));
}
result.Add(new FirstOrderComplexRationalPolynomial(
WWComplex.Zero(), c,
WWComplex.Unity(), WWComplex.Minus(dRoots[k])));
}
return(result);
}
public void Print(string x)
{
if (0 < coeffList.Length)
{
bool bFirst = true;
for (int i = coeffList.Length - 1; 0 <= i; --i)
{
if (coeffList[i].AlmostZero())
{
continue;
}
if (bFirst)
{
bFirst = false;
}
else
{
Console.Write(" + ");
}
if (i == 0)
{
Console.Write("{0}", coeffList[i]);
}
else if (i == 1)
{
Console.Write("{0}*{1}", coeffList[i], x);
}
else
{
Console.Write("{0}*({1}^{2})", coeffList[i], x, i);
}
}
if (!bFirst)
{
Console.Write(" + ");
}
}
Console.Write(" { ");
{
bool bFirst = true;
for (int i = numerCoeffList.Length - 1; 0 <= i; --i)
{
if (numerCoeffList[i].AlmostZero())
{
continue;
}
if (bFirst)
{
bFirst = false;
}
else
{
Console.Write(" + ");
}
if (i == 0)
{
Console.Write("{0}", numerCoeffList[i]);
}
else if (i == 1)
{
Console.Write("{0}*{1}", numerCoeffList[i], x);
}
else
{
Console.Write("{0}*({1}^{2})", numerCoeffList[i], x, i);
}
}
}
Console.Write(" } / { ");
{
for (int i = 0; i < denomRootList.Length; ++i)
{
if (denomRootList[i].AlmostZero())
{
Console.WriteLine(" {0} ", x);
continue;
}
Console.Write("({0}+({1}))", x, WWComplex.Minus(denomRootList[i]));
}
}
Console.WriteLine(" }");
}
