private static void SlowFFT(ComplexFloat[] data)
{
int n = data.Length;
var result = new Complex[n];
var powers = new Complex[n];
var input = new Complex[n];
var array = new Complex[n];
for (int i = n; --i >= 0;)
{
input[i] = new Complex(data[i].Real, data[i].Imaginary);
powers[i] = Complex.FromPolarCoordinates(1.0, Math.PI * 2 * i / n);
}
for (int i = n; --i >= 0;)
{
for (int j = n; --j >= 0;)
{
array[j] = input[j] * powers[i * j % n];
}
result[i] = new Complex(
AccurateSummation.GetAccurateSum(array.Select(x => x.Real)),
AccurateSummation.GetAccurateSum(array.Select(x => x.Imaginary)));
}
for (int i = n; --i >= 0;)
{
data[i] = new ComplexFloat((float)result[i].Real, (float)result[i].Imaginary);
}
}
private static void SlowDCT2(float[] data)
{
int n = data.Length;
double[] cos = new double[n * 4];
for (int i = n * 4; --i >= 0;)
{
cos[i] = Math.Cos(Math.PI * 2 / (n * 4) * i);
}
double[] result = new double[n];
double[] array = new double[n];
for (int i = n; --i >= 0;)
{
for (int j = n; --j >= 0;)
{
array[j] = data[j] * cos[(2 * j + 1) * i % (n * 4)];
}
result[i] = AccurateSummation.GetAccurateSum(array);
}
double scale = Math.Sqrt(2.0);
for (int i = n; --i > 0;)
{
data[i] = (float)(result[i] * scale);
}
data[0] = (float)result[0];
}