DiscreteFourierTransform
math.jwave.transforms

Class DiscreteFourierTransform



  • public class DiscreteFourierTransformextends BasicTransform
    The Discrete Fourier Transform (DFT) is - as the name says - the discrete version of the Fourier Transform applied to a discrete complex valued series. While the DFT can be applied to any complex valued series; of any length, in practice for large series it can take considerable time to compute, while the time taken being proportional to the square of the number on points in the series.
    • Method Summary

      Methods 
      Modifier and TypeMethod and Description
      Complex[]forward(Complex[] arrTime)
      The 1-D forward version of the Discrete Fourier Transform (DFT); The input array arrTime is organized by a class called Complex keeping real and imaginary part of a complex number.
      double[]forward(double[] arrTime)
      The 1-D forward version of the Discrete Fourier Transform (DFT); The input array arrTime is organized by real and imaginary parts of a complex number using even and odd places for the index.
      double[][]forward(double[][] matTime)
      The 2-D forward version of the Discrete Fourier Transform (DFT); The input array matTime is organized by real and imaginary parts of a complex number using even and odd places for the indices.
      double[][][]forward(double[][][] spcTime)
      The 3-D forward version of the Discrete Fourier Transform (DFT);
      Complex[]reverse(Complex[] arrFreq)
      The 1-D reverse version of the Discrete Fourier Transform (DFT); The input array arrFreq is organized by a class called Complex keeping real and imaginary part of a complex number.
      double[]reverse(double[] arrFreq)
      The 1-D reverse version of the Discrete Fourier Transform (DFT); The input array arrFreq is organized by real and imaginary parts of a complex number using even and odd places for the index.
      double[][]reverse(double[][] matFreq)
      The 2-D reverse version of the Discrete Fourier Transform (DFT); The input array matFreq is organized by real and imaginary parts of a complex number using even and odd places for the indices.
      double[][][]reverse(double[][][] spcHilb)
      The 3-D reverse version of the Discrete Fourier Transform (DFT);
    • Constructor Detail

      • DiscreteFourierTransform

        public DiscreteFourierTransform()
        Constructor; does nothing
    • Method Detail

      • forward

        public double[] forward(double[] arrTime)
        The 1-D forward version of the Discrete Fourier Transform (DFT); The input array arrTime is organized by real and imaginary parts of a complex number using even and odd places for the index. For example: arrTime[ 0 ] = real1, arrTime[ 1 ] = imag1, arrTime[ 2 ] = real2, arrTime[ 3 ] = imag2, ... The output arrFreq is organized by the same scheme.
        Specified by:
        forward in class BasicTransform
        Parameters:
        arrTime - coefficients of 1-D time domain
        Returns:
        coefficients of 1-D frequency or Hilbert domain
        See Also:
        BasicTransform.forward(double[])
      • reverse

        public double[] reverse(double[] arrFreq)
        The 1-D reverse version of the Discrete Fourier Transform (DFT); The input array arrFreq is organized by real and imaginary parts of a complex number using even and odd places for the index. For example: arrTime[ 0 ] = real1, arrTime[ 1 ] = imag1, arrTime[ 2 ] = real2, arrTime[ 3 ] = imag2, ... The output arrTime is organized by the same scheme.
        Specified by:
        reverse in class BasicTransform
        Parameters:
        arrFreq - coefficients of 1-D frequency or Hilbert domain
        Returns:
        coefficients of 1-D time domain
        See Also:
        BasicTransform.reverse(double[])
      • forward

        public Complex[] forward(Complex[] arrTime)
        The 1-D forward version of the Discrete Fourier Transform (DFT); The input array arrTime is organized by a class called Complex keeping real and imaginary part of a complex number. The output arrFreq is organized by the same scheme.
        Overrides:
        forward in class BasicTransform
        Parameters:
        arrTime - array of type Complex keeping coefficients of complex numbers
        Returns:
        array of type Complex keeping the discrete fourier transform coefficients
      • reverse

        public Complex[] reverse(Complex[] arrFreq)
        The 1-D reverse version of the Discrete Fourier Transform (DFT); The input array arrFreq is organized by a class called Complex keeping real and imaginary part of a complex number. The output arrTime is organized by the same scheme.
        Overrides:
        reverse in class BasicTransform
        Parameters:
        arrFreq - array of type Complex keeping the discrete fourier transform coefficients
        Returns:
        array of type Complex keeping coefficients of tiem domain
      • forward

        public double[][] forward(double[][] matTime)
        The 2-D forward version of the Discrete Fourier Transform (DFT); The input array matTime is organized by real and imaginary parts of a complex number using even and odd places for the indices. For example: matTime[0][0] = real11, matTime[0][1] = imag11, matTime[0][2] = real12, matTime[0][3] = imag12, matTime[1][0] = real21, matTime[1][1] = imag21, matTime[1][2] = real22, matTime[1][3] = imag2... The output matFreq is organized by the same scheme.
        Overrides:
        forward in class BasicTransform
        Parameters:
        matTime - coefficients of 2-D time domain
        Returns:
        coefficients of 2-D frequency or Hilbert domain
        See Also:
        BasicTransform.forward(double[][])
      • reverse

        public double[][] reverse(double[][] matFreq)
        The 2-D reverse version of the Discrete Fourier Transform (DFT); The input array matFreq is organized by real and imaginary parts of a complex number using even and odd places for the indices. For example: matFreq[0][0] = real11, matFreq[0][1] = imag11, matFreq[0][2] = real12, matFreq[0][3] = imag12, matFreq[1][0] = real21, matFreq[1][1] = imag21, matFreq[1][2] = real22, matFreq[1][3] = imag2... The output matTime is organized by the same scheme.
        Overrides:
        reverse in class BasicTransform
        Parameters:
        matFreq - coefficients of 2-D frequency or Hilbert domain
        Returns:
        coefficients of 2-D time domain
        See Also:
        BasicTransform.reverse(double[][])
      • forward

        public double[][][] forward(double[][][] spcTime)
        The 3-D forward version of the Discrete Fourier Transform (DFT);
        Overrides:
        forward in class BasicTransform
        Parameters:
        spcTime - coefficients of 3-D time domain domain
        Returns:
        coefficients of 3-D frequency or Hilbert domain
        See Also:
        BasicTransform.forward(double[][][])
      • reverse

        public double[][][] reverse(double[][][] spcHilb)
        The 3-D reverse version of the Discrete Fourier Transform (DFT);
        Overrides:
        reverse in class BasicTransform
        Parameters:
        spcHilb - coefficients of 3-D frequency or Hilbert domain
        Returns:
        coefficients of 3-D time domain
        See Also:
        BasicTransform.reverse(double[][][])

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