/// <summary>
/// One dimensional Discrete Fourier Transform.
/// </summary>
///
/// <param name="data">Data to transform.</param>
/// <param name="direction">Transformation direction.</param>
///
public static void DFT(Complex[] data, Direction direction)
{
int n = data.Length;
double arg;
Complex[] dst = new Complex[n];
// for each destination element
for (int i = 0; i < n; i++)
{
dst[i] = Complex.Zero;
arg = -(int)direction * 2.0 * System.Math.PI * (double)i / (double)n;
// sum source elements
for (int j = 0; j < n; j++)
{
dst[i] += data[j] * Complex.FromPolarCoordinates(1.0, j * arg);
}
}
// copy elements
if (direction == Direction.Forward)
{
// devide also for forward transform
for (int i = 0; i < n; i++)
{
data[i] = dst[i] / n;
}
}
else
{
for (int i = 0; i < n; i++)
{
data[i] = dst[i];
}
}
}
/// <summary>
/// Two dimensional Discrete Fourier Transform.
/// </summary>
///
/// <param name="data">Data to transform.</param>
/// <param name="direction">Transformation direction.</param>
///
public static void DFT2(Complex[,] data, Direction direction)
{
int n = data.GetLength(0); // rows
int m = data.GetLength(1); // columns
double arg;
Complex[] dst = new Complex[System.Math.Max(n, m)];
// process rows
for (int i = 0; i < n; i++)
{
for (int j = 0; j < m; j++)
{
dst[j] = Complex.Zero;
arg = -(int)direction * 2.0 * System.Math.PI * (double)j / (double)m;
// sum source elements
for (int k = 0; k < m; k++)
{
dst[j] += data[i, k] * Complex.FromPolarCoordinates(1.0, k * arg);
}
}
// copy elements
if (direction == Direction.Forward)
{
// devide also for forward transform
for (int j = 0; j < m; j++)
{
data[i, j] = dst[j] / m;
}
}
else
{
for (int j = 0; j < m; j++)
{
data[i, j] = dst[j];
}
}
}
// process columns
for (int j = 0; j < m; j++)
{
for (int i = 0; i < n; i++)
{
dst[i] = Complex.Zero;
arg = -(int)direction * 2.0 * System.Math.PI * (double)i / (double)n;
// sum source elements
for (int k = 0; k < n; k++)
{
dst[i] += data[k, j] * Complex.FromPolarCoordinates(1.0, k * arg);
}
}
// copy elements
if (direction == Direction.Forward)
{
// devide also for forward transform
for (int i = 0; i < n; i++)
{
data[i, j] = dst[i] / n;
}
}
else
{
for (int i = 0; i < n; i++)
{
data[i, j] = dst[i];
}
}
}
}
