public static ComplexDouble[] Transform(ComplexDouble[] input)
{
int length = input.Length;
if (length == 1)
{
return new ComplexDouble[] { input[0] }
}
;
ComplexDouble[] evens = new ComplexDouble[length / 2];
ComplexDouble[] odds = new ComplexDouble[length / 2];
for (int i = 0; i < length / 2; i++)
{
evens[i] = input[2 * i];
odds[i] = input[2 * i + 1];
}
ComplexDouble[] evensRes = Transform(evens);
ComplexDouble[] oddsRes = Transform(odds);
for (int i = 0; i < length / 2; i++)
{
oddsRes[i] *= ComplexDouble.FromRF(1, -2 * Math.PI * i / length);
}
ComplexDouble[] res = new ComplexDouble[length];
for (int i = 0; i < length / 2; i++)
{
res[i] = evensRes[i] + oddsRes[i];
res[i + length / 2] = evensRes[i] - oddsRes[i];
}
return(res);
}
public static ComplexDouble FromRF(double r, double f)
{
ComplexDouble res = new ComplexDouble();
res.a = r * Math.Cos(f);
res.b = r * Math.Sin(f);
return(res);
}
public static ComplexDouble FromAB(double a, double b)
{
ComplexDouble res = new ComplexDouble();
res.a = a;
res.b = b;
return(res);
}
static ComplexDouble ImgExponent(double power)
{
return(ComplexDouble.FromRF(1, power));
}
public static ComplexDouble operator *(ComplexDouble z1, ComplexDouble z2)
{
return(ComplexDouble.FromAB(z1.a * z2.a - z1.b * z2.b, z1.a * z2.b + z2.a * z1.b));
}
public static ComplexDouble operator *(ComplexDouble z, double x)
{
return(ComplexDouble.FromAB(z.a * x, z.b * x));
}
public static ComplexDouble operator +(ComplexDouble z1, ComplexDouble z2)
{
return(ComplexDouble.FromAB(z1.a + z2.a, z1.b + z2.b));
}
public static ComplexDouble[] Transform(double[] input)
{
return(Transform(input.Select(x => ComplexDouble.FromAB(x, 0)).ToArray()));
}
