<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 ) &rarr; 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 ) &rarr; void<br>
<hr>
<a name="getInstance"></a>
<h2>getInstance</h2>
getInstance( int n ) &rarr; <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 ) &rarr; 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(  ) &rarr; 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 ) &rarr; 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 ) &rarr; void<br>