<h2>org.das2.math.fft.jnt.ComplexDoubleFFT</h2><p>Abstract Class representing FFT's of complex, double precision data. Concrete classes are typically named ComplexDoubleFFT_<i>method</i>, implement the FFT using some particular method. <P> Complex data is represented by 2 double values in sequence: the real and imaginary parts. Thus, in the default case (i0=0, stride=2), N data points is represented by a double array dimensioned to 2*N. To support 2D (and higher) transforms, an offset, i0 (where the first element starts) and stride (the distance from the real part of one value, to the next: at least 2 for complex values) can be supplied. The physical layout in the array data, of the mathematical data d[i] is as follows: <PRE> Re(d[i]) = data[i0 + stride*i] Im(d[i]) = data[i0 + stride*i+1] </PRE> The transformed data is returned in the original data array in <a href="package-summary.html#wraparound">wrap-around</A> order.</p> <h2>ComplexDoubleFFT( int n )</h2> <p>Create an FFT for transforming n points of complex, double precision data.</p> <hr> <a name="backtransform"></a> <h2>backtransform</h2> backtransform( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/math/fft/ComplexArray/Double.html'>org.das2.math.fft.ComplexArray.Double</a> data ) → void <p></p> <h3>Parameters</h3> data - a ComplexArray.Double <h3>Returns:</h3> void (returns nothing) <br><br> <a href="https://github.com/autoplot/dev/search?q=backtransform&unscoped_q=backtransform">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/math/fft/jnt/ComplexDoubleFFT.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/math/fft/jnt/ComplexDoubleFFT.html#backtransform">[view on old javadoc]</a> <a href="https://saturn.physics.uiowa.edu/svn/das2/dasCore/community/autoplot2011/trunk/dasCore/src/org/das2/math/fft/jnt/ComplexDoubleFFT.java">[view source]</a> <br> <br> backtransform( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/math/fft/ComplexArray/Double.html'>org.das2.math.fft.ComplexArray.Double</a> data, int i0, int stride ) → void<br> <hr> <a name="getInstance"></a> <h2>getInstance</h2> getInstance( int n ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/math/fft/jnt/ComplexDoubleFFT.html'>org.das2.math.fft.jnt.ComplexDoubleFFT</a> <p>Creates an instance of a subclass of ComplexDoubleFFT appropriate for data of n elements.</p> <h3>Parameters</h3> n - an int <h3>Returns:</h3> org.das2.math.fft.jnt.ComplexDoubleFFT <br><br> <a href="https://github.com/autoplot/dev/search?q=getInstance&unscoped_q=getInstance">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/math/fft/jnt/ComplexDoubleFFT.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/math/fft/jnt/ComplexDoubleFFT.html#getInstance">[view on old javadoc]</a> <a href="https://saturn.physics.uiowa.edu/svn/das2/dasCore/community/autoplot2011/trunk/dasCore/src/org/das2/math/fft/jnt/ComplexDoubleFFT.java">[view source]</a> <br> <br> <hr> <a name="inverse"></a> <h2>inverse</h2> inverse( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/math/fft/ComplexArray/Double.html'>org.das2.math.fft.ComplexArray.Double</a> data ) → void <p>Compute the (nomalized) inverse FFT of data, leaving it in place.</p> <h3>Parameters</h3> data - a ComplexArray.Double <h3>Returns:</h3> void (returns nothing) <br><br> <a href="https://github.com/autoplot/dev/search?q=inverse&unscoped_q=inverse">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/math/fft/jnt/ComplexDoubleFFT.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/math/fft/jnt/ComplexDoubleFFT.html#inverse">[view on old javadoc]</a> <a href="https://saturn.physics.uiowa.edu/svn/das2/dasCore/community/autoplot2011/trunk/dasCore/src/org/das2/math/fft/jnt/ComplexDoubleFFT.java">[view source]</a> <br> <br> <hr> <a name="normalization"></a> <h2>normalization</h2> normalization( ) → double <p>Return the normalization factor. Multiply the elements of the backtransform'ed data to get the normalized inverse.</p> <h3>Returns:</h3> double <br><br> <a href="https://github.com/autoplot/dev/search?q=normalization&unscoped_q=normalization">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/math/fft/jnt/ComplexDoubleFFT.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/math/fft/jnt/ComplexDoubleFFT.html#normalization">[view on old javadoc]</a> <a href="https://saturn.physics.uiowa.edu/svn/das2/dasCore/community/autoplot2011/trunk/dasCore/src/org/das2/math/fft/jnt/ComplexDoubleFFT.java">[view source]</a> <br> <br> <hr> <a name="transform"></a> <h2>transform</h2> transform( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/math/fft/ComplexArray/Double.html'>org.das2.math.fft.ComplexArray.Double</a> data ) → void <p>Compute the Fast Fourier Transform of data leaving the result in data. The array data must be dimensioned (at least) 2*n, consisting of alternating real and imaginary parts.</p> <h3>Parameters</h3> data - a ComplexArray.Double <h3>Returns:</h3> void (returns nothing) <br><br> <a href="https://github.com/autoplot/dev/search?q=transform&unscoped_q=transform">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/math/fft/jnt/ComplexDoubleFFT.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/math/fft/jnt/ComplexDoubleFFT.html#transform">[view on old javadoc]</a> <a href="https://saturn.physics.uiowa.edu/svn/das2/dasCore/community/autoplot2011/trunk/dasCore/src/org/das2/math/fft/jnt/ComplexDoubleFFT.java">[view source]</a> <br> <br> transform( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/math/fft/ComplexArray/Double.html'>org.das2.math.fft.ComplexArray.Double</a> data, int i0, int stride ) → void<br>