rcond:

Syntax:	rcond( A )

Description:	

	Rcond estimates the recipricol of the condition number of the
	input matrix A. rcond() uses the LAPACK routines DGECON, or
	ZGECON.

	Probably the most published way to compute the condition
	number of a matrix is:

	Kcond = ||A|| * ||inv(A)||

	Another method is to use the 1st and last singular values of
	A:

	Kcond = sigma(1)/sigma(n)

	rcond() computes an ESTIMATE of the recipricol of the
	condition number without computing all of the columns of
	inv(A). For more information see the LAPACK User's Guide.

	Example:

		> A = [1,2,3;4,5,6;7,8,9]
		 A =
		        1          2          3  
		        4          5          6  
		        7          8          9  
		> # Get the condition number of A
		> 1/rcond (A)
		 4.54e+17  
		> A[3;3] = 0
		 A =
		        1          2          3  
		        4          5          6  
		        7          8          0  
		> 1/rcond (A)
		     51.7  

See Also  inv, det, lu
