|
public Transform ( IList |
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| values | IList |
The series to transform. |
| return | ScalarValue[] | |
public BluesteinTransformlet(int R, int N, ScalarValue[] u)
: base(R, N, u)
{
// figure out the right Bluestein length and create a transformer for it
Nb = SetBluesteinLength(2 * R - 1);
ft = new Fourier(Nb);
// compute the Bluestein coeffcients and compute the FT of the filter based on them
b = ComputeBluesteinCoefficients(R);
var c = new ScalarValue[Nb];
c[0] = ScalarValue.One;
for (int i = 1; i < R; i++)
{
c[i] = b[i].Conjugate();
c[Nb - i] = c[i];
}
for (int i = R; i <= Nb - R; i++)
{
c[i] = ScalarValue.Zero;
}
bt = ft.Transform(c);
}
public override void FftKernel(ScalarValue[] x, ScalarValue[] y, int y0, int dy, int sign)
{
// create c = b x and transform it into Fourier space
var c = new ScalarValue[Nb];
if (sign > 0)
{
for (int i = 0; i < R; i++)
{
c[i] = b[i] * x[i];
}
}
else
{
for (int i = 0; i < R; i++)
{
c[i] = b[i] * x[i].Conjugate();
}
}
for (int i = R; i < c.Length; i++)
{
c[i] = ScalarValue.Zero;
}
var ct = ft.Transform(c);
// multiply b-star and c = b x in Fourier space, and inverse transform the product back into configuration space
for (int i = 0; i < Nb; i++)
{
ct[i] = ct[i] * bt[i];
}
c = ft.InverseTransform(ct);
// read off the result
if (sign > 0)
{
for (int i = 0; i < R; i++)
{
y[y0 + i * dy] = b[i] * c[i];
}
}
else
{
for (int i = 0; i < R; i++)
{
y[y0 + i * dy] = b[i].Conjugate() * c[i].Conjugate();
}
}
}
public BluesteinTransformlet(int R, int N, ScalarValue[] u)
: base(R, N, u)
{
// figure out the right Bluestein length and create a transformer for it
Nb = SetBluesteinLength(2 * R - 1);
ft = new Fourier(Nb);
// compute the Bluestein coeffcients and compute the FT of the filter based on them
b = ComputeBluesteinCoefficients(R);
var c = new ScalarValue[Nb];
c[0] = ScalarValue.One;
for (int i = 1; i < R; i++)
{
c[i] = b[i].Conjugate();
c[Nb - i] = c[i];
}
for (int i = R; i <= Nb - R; i++)
c[i] = ScalarValue.Zero;
bt = ft.Transform(c);
}
public MatrixValue Function(MatrixValue M)
{
var transpose = false;
if (M.DimensionX > M.DimensionY)
{
transpose = true;
M = M.Transpose();
}
var fft = new Fourier(M.DimensionY);
for (var i = 1; i <= M.DimensionX; i++)
{
var values = new ScalarValue[M.DimensionY];
for (var j = 1; j <= M.DimensionY; j++)
{
values[j - 1] = M[j, i];
}
values = fft.Transform(values);
for (var j = 1; j <= M.DimensionY; j++)
{
M[j, i] = values[j - 1];
}
}
if (transpose)
{
return M.Transpose();
}
return M;
}
