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CircStats: S-PLUS Functions for Circular Statistics
           Version 2.0
           September, 2004
           Created and tested using MS Windows 2000 and XP, with S-PLUS 6.2 for Windows
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Version 2.0 has the following corrections of bugs and novel features:

*** Corrections
  
  1. circ.reg:  
       In versions of S-PLUS later than 4.5, circ.reg had problems
       b/c the result was not initialized explicitly as a list.  
       The result returned by the function is now explicitly initialized
       as a list.  Also, there was an error in the way the function 
       assessed whether higher order terms were needed in the trigonometric
       polynomials fit to the data.  In Version 1.0, a higher order model 
       was deemed unnecessary if either of the sin or cos models did not 
       require a higher order model.  In Version 2.0, a higher order model
       is deemed necessary overall if either of the sin or cos models are
       inadequate at a given level.

  2. circ.plot and rose.diag: 
       In version 1.0 negative angles were plotted incorrectly.  This bug
       has been corrected.  See further information regarding these two 
       functions below.

*** Enhancements/Changes

  1. The "degree" option has been removed from the r.test and v0.test functions.  
     The "rad" (radians) option has been removed from the list of possible 
     arguments for the rao.spacing function.  The entire library of functions 
     is now consistent in that circular arguments are assumed to be measured 
     in radians.

  2. The functions circ.plot and rose.diag have been merged into one plotting
     function, circ.plot.  A rose diagram can now be requested as an option.
     Other options were added for circ.plot, allowing for data to be measured
     in various orientations around the circle, and with various 0 directions.
     Options to affect the labelling and points drawn on the plotting device have
     also been enhanced.

  3. The function nCk has been removed from the library, as S-PLUS now has the 
     function choose to perform the same operation. Circ.range has been changed
     to utilize the choose function instead of nCk.

  4. The function circ.aov has been added to the library.  This function implements
     several one-way classification tests for common mean directions across several 
     groups of measurements.

  5. The function circ.lin.reg has been added to the library.  This function 
     implements the Fisher and Lee (1992) circular/linear regression model, predicting
     a circular response from a set of linear covariates.

  6. The function equal.kappa.test has been added to the library.  This function
     implements a test for common concentration parameters across several groups of  
     measurements, assuming measurements are coming from a von Mises distribution.

  7. The function ls.circle has been added to the library.  This function implements
     a method of computing least squares estimates of the parameters of a circle, given
     a set of measurements in two dimensions.  The function plot.ls.circle makes a 
     graph of the data with the estimated least squares circle.



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Please address questions and comments regarding the library to:

Ulric J. Lund
Department of Statistics
California Polytechnic State University
San Luis Obispo, CA 93407

Email: ulund@calpoly.edu
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