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   Parametric Plotting.
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   Form:
   y = ParamPlot( data, yName, xName );
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   Inputs
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   data                (.)  Parametric Plotting Data Structure
   yName               (:)  Name of variable to plot
   xName               (:)  Name of x-axis variable
   figName             (:)  Figure title (optional)
   figNum              (1)  Figure number (optional)

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   Outputs
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   y                 {i}(j,k) i cells of j vectors, k long

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