Cosmetic changes to transform.FastFourierTransformer (MATH-677).
git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1212260 13f79535-47bb-0310-9956-ffa450edef68
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@ -52,9 +52,8 @@ public class FastFourierTransformer implements Serializable {
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/** Serializable version identifier. */
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/** Serializable version identifier. */
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static final long serialVersionUID = 5138259215438106000L;
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static final long serialVersionUID = 5138259215438106000L;
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/**
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/**
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* {@code true} if the orthogonal version of the FFT should be used.
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* {@code true} if the unitary version of the DFT should be used.
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*
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*
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* @see #create()
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* @see #create()
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* @see #createUnitary()
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* @see #createUnitary()
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@ -64,19 +63,12 @@ public class FastFourierTransformer implements Serializable {
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/** The roots of unity. */
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/** The roots of unity. */
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private RootsOfUnity roots = new RootsOfUnity();
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private RootsOfUnity roots = new RootsOfUnity();
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/** Construct a default transformer. */
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private FastFourierTransformer() {
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super();
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this.unitary = false;
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}
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/**
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/**
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* Creates a new instance of this class, with various normalization
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* Creates a new instance of this class, with various normalization
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* conventions.
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* conventions.
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*
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*
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* @param unitary {@code false} if the direct Fourier transform is
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* @param unitary {@code false} if the DFT is <em>not</em> to be scaled,
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* <em>not</em> to be scaled, {@code true} if it is to be scaled so as to
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* {@code true} if it is to be scaled so as to make the transform unitary.
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* make the transform unitary.
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* @see #create()
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* @see #create()
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* @see #createUnitary()
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* @see #createUnitary()
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*/
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*/
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@ -88,17 +80,18 @@ public class FastFourierTransformer implements Serializable {
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* <p>
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* <p>
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* Returns a new instance of this class. The returned transformer uses the
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* Returns a new instance of this class. The returned transformer uses the
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* normalizing conventions described below.
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* normalizing conventions described below.
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* </p>
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* <ul>
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* <ul>
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* <li>Forward transform:
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* <li>Forward transform:
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* y<sub>n</sub> = ∑<sub>k=0</sub><sup>N-1</sup>
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* y<sub>n</sub> = ∑<sub>k=0</sub><sup>N-1</sup>
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* x<sub>k</sub> exp(-2πi n k / N),</li>
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* x<sub>k</sub> exp(-2πi n k / N),</li>
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* <li>Inverse transform:
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* <li>Inverse transform:
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* x<sub>k</sub> = N<sup>-1</sup> ∑<sub>n=0</sub><sup>N-1</sup>
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* x<sub>k</sub> = N<sup>-1</sup> ∑<sub>n=0</sub><sup>N-1</sup>
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* y<sub>n</sub> exp(2πi n k / N).</li>
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* y<sub>n</sub> exp(2πi n k / N),</li>
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* </ul>
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* </ul>
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* where N is the size of the data sample.
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* </p>
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*
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*
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* @return a new FFT transformer, with "standard" normalizing conventions
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* @return a new DFT transformer, with "standard" normalizing conventions
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*/
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*/
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public static FastFourierTransformer create() {
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public static FastFourierTransformer create() {
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return new FastFourierTransformer(false);
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return new FastFourierTransformer(false);
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@ -116,7 +109,7 @@ public class FastFourierTransformer implements Serializable {
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* x<sub>k</sub> = N<sup>-1/2</sup> ∑<sub>n=0</sub><sup>N-1</sup>
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* x<sub>k</sub> = N<sup>-1/2</sup> ∑<sub>n=0</sub><sup>N-1</sup>
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* y<sub>n</sub> exp(2πi n k / N),</li>
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* y<sub>n</sub> exp(2πi n k / N),</li>
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* </ul>
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* </ul>
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* which make the transform unitary.
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* which make the transform unitary. N is the size of the data sample.
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* </p>
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* </p>
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*
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*
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* @return a new FFT transformer, with unitary normalizing conventions
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* @return a new FFT transformer, with unitary normalizing conventions
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