<h2>org.das2.qds.util.FFTUtil</h2><p>Utilities for FFT operations, such as getting the frequencies for each bin and fftPower.</p> <h2>FFTUtil( )</h2> <p></p> <hr> <a name="fft"></a> <h2>fft</h2> fft( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/GeneralFFT.html'>org.das2.qds.math.fft.GeneralFFT</a> fft, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> vds, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> weights ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>Perform the fft to get real and imaginary components for intervals.</p> <h3>Parameters</h3> fft - FFT code to use, such as GeneralFFT.newDoubleFFT(len) <br> vds - QDataSet rank 1 dataset with depend 0 units TimeLocationUnits. <br> weights - QDataSet rank 1 dataset containing weights, as in hanning. null indicates no weights. <h3>Returns:</h3> the rank 2 FFT <br><br> <a href="https://github.com/autoplot/dev/search?q=fft&unscoped_q=fft">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#fft">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l227">[view source]</a> <br> <br> fft( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/GeneralFFT.html'>org.das2.qds.math.fft.GeneralFFT</a> fft, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> vds ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/ComplexArray/Double.html'>org.das2.qds.math.fft.ComplexArray.Double</a><br> <hr> <a name="fftPower"></a> <h2>fftPower</h2> fftPower( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/GeneralFFT.html'>org.das2.qds.math.fft.GeneralFFT</a> fft, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> vds ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p></p> <h3>Parameters</h3> fft - a GeneralFFT <br> vds - a QDataSet <h3>Returns:</h3> org.das2.qds.QDataSet <br><br> <a href="https://github.com/autoplot/dev/search?q=fftPower&unscoped_q=fftPower">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#fftPower">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l33">[view source]</a> <br> <br> fftPower( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/GeneralFFT.html'>org.das2.qds.math.fft.GeneralFFT</a> fft, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> vds, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> weights ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a><br> fftPower( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/GeneralFFT.html'>org.das2.qds.math.fft.GeneralFFT</a> fft, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> vds, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> weights, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> powxTags ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a><br> <hr> <a name="getFrequencyDomainTags"></a> <h2>getFrequencyDomainTags</h2> getFrequencyDomainTags( double fs, int size ) → double[] <p></p> <h3>Parameters</h3> fs - the sampling frequency <br> size - the size of the time domain data. <h3>Returns:</h3> the frequencies of the bins <br><br> <a href="https://github.com/autoplot/dev/search?q=getFrequencyDomainTags&unscoped_q=getFrequencyDomainTags">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#getFrequencyDomainTags">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l430">[view source]</a> <br> <br> getFrequencyDomainTags( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> timeDomainTags ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a><br> <hr> <a name="getFrequencyDomainTagsForPower"></a> <h2>getFrequencyDomainTagsForPower</h2> getFrequencyDomainTagsForPower( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> dep0 ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>get the frequency tags, for use when calculating the power in each channel. This removes the DC channel, and folds over the negative frequencies. This also keeps a cache for performance.</p> <h3>Parameters</h3> dep0 - the timetags. <h3>Returns:</h3> the frequency tags. <br><br> <a href="https://github.com/autoplot/dev/search?q=getFrequencyDomainTagsForPower&unscoped_q=getFrequencyDomainTagsForPower">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#getFrequencyDomainTagsForPower">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l345">[view source]</a> <br> <br> <hr> <a name="getTimeDomainTags"></a> <h2>getTimeDomainTags</h2> getTimeDomainTags( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> frequencyDomainTags ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>return the time domain tags for inverse fft.</p> <h3>Parameters</h3> frequencyDomainTags - a QDataSet <h3>Returns:</h3> the time Domain Tags <br><br> <a href="https://github.com/autoplot/dev/search?q=getTimeDomainTags&unscoped_q=getTimeDomainTags">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#getTimeDomainTags">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l449">[view source]</a> <br> <br> <hr> <a name="getWindow10PercentEdgeCosine"></a> <h2>getWindow10PercentEdgeCosine</h2> getWindow10PercentEdgeCosine( int size ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>Window with ones in the middle, and then the last 10% taper with cos.</p> <h3>Parameters</h3> size - the window size <h3>Returns:</h3> window <br><br> <a href="https://github.com/autoplot/dev/search?q=getWindow10PercentEdgeCosine&unscoped_q=getWindow10PercentEdgeCosine">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#getWindow10PercentEdgeCosine">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l115">[view source]</a> <br> <br> <hr> <a name="getWindowHanning"></a> <h2>getWindowHanning</h2> getWindowHanning( int size ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>return a "Hanning" (Hann) window of the given size.</p> <h3>Parameters</h3> size - an int <h3>Returns:</h3> a QDataSet <br><br> <a href="https://github.com/autoplot/dev/search?q=getWindowHanning&unscoped_q=getWindowHanning">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#getWindowHanning">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l137">[view source]</a> <br> <br> <hr> <a name="getWindowUnity"></a> <h2>getWindowUnity</h2> getWindowUnity( int size ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>Window that is all ones, also called a boxcar.</p> <h3>Parameters</h3> size - the window size <h3>Returns:</h3> window <br><br> <a href="https://github.com/autoplot/dev/search?q=getWindowUnity&unscoped_q=getWindowUnity">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#getWindowUnity">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l89">[view source]</a> <br> <br> <hr> <a name="ifft"></a> <h2>ifft</h2> ifft( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/GeneralFFT.html'>org.das2.qds.math.fft.GeneralFFT</a> fft, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> vds, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> weights ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>Perform the inverse fft to get real and imaginary components for intervals.</p> <h3>Parameters</h3> fft - FFT code to use, such as GeneralFFT.newDoubleFFT(len) <br> vds - QDataSet rank 2 dataset with depend 0 units TimeLocationUnits and depend_1=['real','imaginary']. <br> weights - QDataSet rank 1 dataset containing weights, as in hanning. null indicates no weights. <h3>Returns:</h3> the rank 2 FFT <br><br> <a href="https://github.com/autoplot/dev/search?q=ifft&unscoped_q=ifft">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#ifft">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l273">[view source]</a> <br> <br> ifft( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/GeneralFFT.html'>org.das2.qds.math.fft.GeneralFFT</a> fft, <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> vds ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/math/fft/ComplexArray/Double.html'>org.das2.qds.math.fft.ComplexArray.Double</a><br> <hr> <a name="window"></a> <h2>window</h2> window( <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> ds, int size ) → <a href='http://www-pw.physics.uiowa.edu/~jbf/autoplot/doc/org/das2/qds/QDataSet.html'>QDataSet</a> <p>returns a rank 2 dataset from the rank 1 dataset, where the FFT would be run on each of the datasets.</p> <h3>Parameters</h3> ds - rank 1 dataset of length N <br> size - size of each FFT. <h3>Returns:</h3> rank 2 dataset[N/size,size] <br><br> <a href="https://github.com/autoplot/dev/search?q=window&unscoped_q=window">[search for examples]</a> <a href="https://github.com/autoplot/documentation/tree/master/javadoc/org/das2/qds/util/FFTUtil.md">[view on GitHub]</a> <a href="http://www-pw.physics.uiowa.edu/~jbf/autoplot/javadoc2018/org/das2/qds/util/FFTUtil.html#window">[view on old javadoc]</a> <a href="https://sourceforge.net/p/autoplot/code/HEAD/tree/autoplot/trunk/QDataSet/src/org/das2/qds/util/FFTUtil.java#l44">[view source]</a> <br> <br>