factor:

Syntax:	factor ( A )
	factor ( A , TYPE )

Description:

	The factor function computes the LU factorization of the input
	matrix A. Factor returns a list with 3 elements: 

	if A is a general matrix:
		lu	a matrix containing the LU factors
		pvt	a vector containing the pivot indices
		rcond	the inverse of the condition estimate
	Factor utilizes the LAPACK subroutines DGETRF, DGECON or
	ZGETRF, ZGECON.

	if A is a symmetric matrix:
		ldl	a matrix containing the block diagonal matrix
                        D, and the multipliers used to obtain L.
		pvt	a vector containing the pivot indices
		rcond	the inverse of the condition estimate
	Factor utilizes the LAPACK subroutines DSYTRF, DSYCON or
	ZHETRF, ZHECON.

	The user can overide factor's choice of solution type with the
	optional argument TYPE. 

		TYPE = "g" or "G"	The general solution is used.

		TYPE = "s" or "S"	the symmetric solution is used.

	Factor returns the results in the above format, so that they
	may be conveniently used with backsub for repetitive
	solutions. The user-function lu will separate the results from
	factor into separate L and U matrices.

See Also: backsub, inv, lu, solve
