/// <summary>
/// Performs the DFT -- converting a 2D position-domain signal into a 2D frequency-domain signal.
/// </summary>
/// <param name="samples">
/// The samples from an input signal.
/// </param>
/// <param name="outResult">
/// The output array.
/// If it's null or the wrong size, it will be automatically created.
/// Contains the sine/cosine wave amplitudes for each frequency in the signal.
/// </param>
public static void Forward(Complex[,] samples, ref Complex[,] outResult)
{
//Make sure the output array is the right size.
if (outResult == null ||
outResult.GetLength(0) != samples.GetLength(0) ||
outResult.GetLength(1) != samples.GetLength(1))
{
outResult = new Complex[samples.GetLength(0), samples.GetLength(1)];
}
//Perform the 1D DFT along every row and column.
//Row:
Complex[][] dftByRow = new Complex[samples.GetLength(1)][];
ThreadedRunner.Run(NThreads, samples.GetLength(1),
(startY, endY) =>
{
Complex[] sampleLine = new Complex[samples.GetLength(0)];
for (int sampleY = startY; sampleY <= endY; ++sampleY)
{
//Populate the sample array.
for (int sampleX = 0; sampleX < samples.GetLength(0); ++sampleX)
{
sampleLine[sampleX] = samples[sampleX, sampleY];
}
//Run the dft.
dftByRow[sampleY] = Algo1D.Forward(sampleLine);
}
});
//Column:
var _outResult = outResult; //ref variables can't be used inside a lambda.
ThreadedRunner.Run(NThreads, samples.GetLength(0),
(startX, endX) =>
{
Complex[] sampleLine = new Complex[samples.GetLength(1)];
for (int sampleX = startX; sampleX <= endX; ++sampleX)
{
//Populate the sample array.
for (int sampleY = 0; sampleY < samples.GetLength(1); ++sampleY)
{
sampleLine[sampleY] = dftByRow[sampleY][sampleX];
}
//Run the dft.
var results = Algo1D.Forward(sampleLine);
for (int sampleY = 0; sampleY < samples.GetLength(1); ++sampleY)
{
_outResult[sampleX, sampleY] = results[sampleY];
}
}
});
}
/// <summary>
/// Performs the inverse DFT -- converting a frequency-domain signal
/// back into a 2D position-domain signal.
/// </summary>
/// <param name="dftResults">
/// The frequency-domain signal.
/// </param>
/// <param name="outSamples">
/// The position-domain signal samples.
/// If the array is null or the wrong size, it will be automatically created.
/// </param>
public static void Inverse(Complex[,] dftResults, ref Complex[,] outSamples)
{
//Make sure the output array is the right size.
if (outSamples == null ||
outSamples.GetLength(0) != dftResults.GetLength(0) ||
outSamples.GetLength(1) != dftResults.GetLength(1))
{
outSamples = new Complex[dftResults.GetLength(0), dftResults.GetLength(1)];
}
//Perform the 1D inverse DFT along each row/column.
//Column:
Complex[][] inverseDFTByCol = new Complex[dftResults.GetLength(0)][];
ThreadedRunner.Run(NThreads, dftResults.GetLength(0),
(startX, endX) =>
{
Complex[] sampleLine = new Complex[dftResults.GetLength(1)];
for (int sampleX = startX; sampleX <= endX; ++sampleX)
{
//Populate the sample array.
for (int sampleY = 0; sampleY < dftResults.GetLength(1); ++sampleY)
{
sampleLine[sampleY] = dftResults[sampleX, sampleY];
}
//Run the dft.
inverseDFTByCol[sampleX] = Algo1D.Inverse(sampleLine);
}
});
//Row:
var _outSamples = outSamples; //Can't use a ref variable in a lambda.
ThreadedRunner.Run(NThreads, dftResults.GetLength(1),
(startY, endY) =>
{
Complex[] sampleLine = new Complex[dftResults.GetLength(0)];
for (int sampleY = startY; sampleY <= endY; ++sampleY)
{
//Populate the sample array.
for (int sampleX = 0; sampleX < dftResults.GetLength(0); ++sampleX)
{
sampleLine[sampleX] = inverseDFTByCol[sampleX][sampleY];
}
//Run the dft.
var results = Algo1D.Inverse(sampleLine);
for (int sampleX = 0; sampleX < dftResults.GetLength(0); ++sampleX)
{
_outSamples[sampleX, sampleY] = results[sampleX];
}
}
});
}
