UniDyn--Demo-03.nb

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John A. Marohn
jam99@cornell.edu
Cornell University\
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Introductory example illustrating one-dimensional DFT data ordering\
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\[OpenCurlyDoubleQuote]Spike\[CloseCurlyDoubleQuote] the data with a dc \
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To plot, set the total number of points (NN) and the total time (T).  We set \
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From NN and T$final we derive the time step (dt) and the frequency step (df). \
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Take the Fourier transform and plot the absolute value of the Fourier \
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Now the plot looks right.  Check that there is a peak at zero frequency due \
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Print out the frequency of the peak in the absolute value of the Fourier \
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Define our own one-dimensional DFT module and illustrate aliasing\
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Test drive the module.  Feed the DFFT program a signal consisting of a cosine \
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Fourier transform a decaying sine wave.  How is the Fourier transform \
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Change how we make the linear combination of the Cos[] and Sin[] signals.\
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Cell["When the data abruptly stops ... you get \[OpenCurlyDoubleQuote]sinc\
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If, on the other hand, you force the data to decay ... then the sinc() \
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The Exp[] function is not exactly zero at the cutoff time of 1 second in the \
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