/// <summary>
/// Forward Hilbert transform.
/// </summary>
/// <param name="A">Array</param>
/// <returns>Array</returns>
public Complex32[] Forward(Complex32[] A)
{
int N = A.Length;
Complex32[] F = FFT.Forward(A);
HilbertTransform.hilbertf(F, N);
F = FFT.Backward(F);
return(HilbertTransform.hilbertb(A, F, N));
}
/// <summary>
/// Forward cosine transform.
/// </summary>
/// <param name="A">Array</param>
/// <returns>Array</returns>
public float[] Forward(float[] A)
{
int N = A.Length, N2 = N / 2, i, k;
Complex32[] B = new Complex32[N];
for (i = 0; i < N2; i++)
{
var j = 2 * i;
B[i] = A[j];
B[i + N2] = A[N - j - 1];
}
B = FFT.Forward(B);
float[] C = new float[N];
Complex32 c = -Maths.I * Maths.Pi / (2 * N);
for (k = 0; k < N; k++)
{
C[k] = 2.0f * (B[k] * Maths.Exp(c * k)).Real / Maths.Sqrt(2 * N);
}
C[0] = C[0] / Maths.Sqrt2; // DCT-I
return(C);
}
/// <summary>
/// Forward cosine transform.
/// </summary>
/// <param name="A">Array</param>
/// <returns>Array</returns>
public float[] Forward(float[] A)
{
int N = A.Length, N2 = N * 2, i, k;
Complex32[] B = new Complex32[N2];
for (i = 0; i < N; i++)
{
B[i] = A[i];
}
B = FFT.Forward(B);
float[] C = new float[N];
Complex32 c = -Maths.I * Maths.Pi / N;
for (k = 0; k < N; k++)
{
C[k] = 2.0f * (B[k] * Maths.Exp(c * k)).Imag;
}
C[0] = A[N - 1] / Maths.Sqrt2;
return(C);
}
/// <summary>
/// Forward Hartley transform.
/// </summary>
/// <param name="A">Array</param>
/// <returns>Array</returns>
public float[] Forward(float[] A)
{
Complex32[] B = Matrice.ToComplex(A);
B = FFT.Forward(B);
int length = A.Length, i;
float[] Hk = new float[length];
for (i = 0; i < length; i++)
{
Hk[i] = B[i].Real - B[i].Imag;
}
return(Hk);
}
/// <summary>
/// Forward Laplace transform.
/// </summary>
/// <param name="A">Array</param>
/// <returns>Array</returns>
public Complex32[] Forward(Complex32[] A)
{
// Fourier transform:
Complex32[] B = FFT.Forward(A);
// Fourier to Laplace transform:
laplace(B, sigma);
return(B);
}
