2007-05-18  Jun Yan  <jyan@p-lnx401.stat.uiowa.edu>

	* Association measures are exported into the namespace:
	kendallsTau, spearmansRho, and tailIndex. Calibration
	functions are implemented for Kendall's tau and Spearman's rho. 

	* Extreme value copula class is implemented. This class 
	includes Galambos, Husler-Reiss.

	* Added Archimedean copula Ali-Mikhail-Haq.

	* Added Plackett copula.

2007-04-28  Jun Yan  <jyan@p-lnx401.stat.uiowa.edu>

	* The three Archemedean copulas (clayton, frank, and gumbel) now
	have their density expressions imported from mathematica, after 
	some symbolic simplification, which helps to eliminate some numerical
	precisions problems on the boundary of the unit square. 

	Frank copula has the most complicated expressions. On 4GB memory
	machine it ran out of memory for dim = 10. So for frank copula, the
	maximum dimension implemented is dim = 6.	
	
	The symbolic expressions are processed in R with function deriv
	to generate efficient algorithmic expressions.


