/// <summary>
/// Gets an evaluation function depending on the requested type of output.
/// </summary>
/// <param name="kind">Requested type of output.</param>
/// <returns>A function that takes the real part and the imaginary part of one Fourier transformation point and returns the requested output value.</returns>
/// <exception cref="System.NotImplementedException">Triggered if the requested output type is not supported.</exception>
private Func <double, double, double> GetEvalFunction(RealFourierTransformationOutputKind kind)
{
int numRows = NumberOfRows;
int numCols = NumberOfColumns; // make this two variables local because they get included in the functions;
double fac = 1.0 / (((double)numCols) * numRows);
switch (kind)
{
case RealFourierTransformationOutputKind.RealPart:
return((re, im) => re * fac);
case RealFourierTransformationOutputKind.ImaginaryPart:
return((re, im) => im * fac);
case RealFourierTransformationOutputKind.Amplitude:
return((re, im) => Math.Sqrt(re * re + im * im) * fac);
case RealFourierTransformationOutputKind.Phase:
return((re, im) => Math.Atan2(im, re));
case RealFourierTransformationOutputKind.Power:
return((re, im) => (re * re + im * im) * fac * fac);
default:
throw new NotImplementedException(string.Format("The transformation kind {0} is not implemented!", kind));
}
}
/// <summary>
/// Gets a result of the Fourier transformation. Here, the row and column frequency of zero is located in the center of the matrix.
/// </summary>
/// <param name="rowFraction">Number (0..1) that designates the fraction of output row frequencies that should be included in the result.</param>
/// <param name="columnFraction">Number (0..1) that designates the fraction of output column frequencies that should be included in the result.</param>
/// <param name="kind">Requested type of output.</param>
/// <param name="matrix">The matrix that accomodates the result.</param>
/// <param name="rowFrequencies">Vector that accomodates the row frequencies.</param>
/// <param name="columnFrequencies">Vector that accomodates the column frequencies.</param>
/// <exception cref="System.InvalidOperationException">Before getting any result, you must execute the Fourier transformation first (by calling Execute).</exception>
public void GetResultCentered(double rowFraction, double columnFraction, RealFourierTransformationOutputKind kind, out IMatrix <double> matrix, out IROVector <double> rowFrequencies, out IROVector <double> columnFrequencies)
{
GetResultCentered(rowFraction, columnFraction, GetEvalFunction(kind), out matrix, out rowFrequencies, out columnFrequencies);
}
/// <summary>
/// Gets a result of the Fourier transformation. Here, the row and column frequency of zero is located in the center of the matrix.
/// </summary>
/// <param name="rowFraction">Number (0..1) that designates the fraction of output row frequencies that should be included in the result.</param>
/// <param name="columnFraction">Number (0..1) that designates the fraction of output column frequencies that should be included in the result.</param>
/// <param name="kind">Requested type of output.</param>
/// <param name="matrix">The matrix that accomodates the result.</param>
/// <param name="rowFrequencies">Vector that accomodates the row frequencies.</param>
/// <param name="columnFrequencies">Vector that accomodates the column frequencies.</param>
/// <exception cref="System.InvalidOperationException">Before getting any result, you must execute the Fourier transformation first (by calling Execute).</exception>
public void GetResultCentered(double rowFraction, double columnFraction, RealFourierTransformationOutputKind kind, out IMatrix matrix, out IROVector rowFrequencies, out IROVector columnFrequencies)
{
GetResultCentered(rowFraction, columnFraction, GetEvalFunction(kind), out matrix, out rowFrequencies, out columnFrequencies);
}
/// <summary>
/// Gets an evaluation function depending on the requested type of output.
/// </summary>
/// <param name="kind">Requested type of output.</param>
/// <returns>A function that takes the real part and the imaginary part of one Fourier transformation point and returns the requested output value.</returns>
/// <exception cref="System.NotImplementedException">Triggered if the requested output type is not supported.</exception>
private Func<double, double, double> GetEvalFunction(RealFourierTransformationOutputKind kind)
{
int numRows = NumberOfRows;
int numCols = NumberOfColumns; // make this two variables local because they get included in the functions;
double fac = 1.0 / (((double)numCols) * numRows);
switch (kind)
{
case RealFourierTransformationOutputKind.RealPart:
return (re, im) => re * fac;
case RealFourierTransformationOutputKind.ImaginaryPart:
return (re, im) => im * fac;
case RealFourierTransformationOutputKind.Amplitude:
return (re, im) => Math.Sqrt(re * re + im * im) * fac;
case RealFourierTransformationOutputKind.Phase:
return (re, im) => Math.Atan2(im, re);
case RealFourierTransformationOutputKind.Power:
return (re, im) => (re * re + im * im) * fac * fac;
default:
throw new NotImplementedException(string.Format("The transformation kind {0} is not implemented!", kind));
}
}