zgetc2(l) [redhat man page]

ZGETC2(l)								 )								 ZGETC2(l)

NAME

       ZGETC2 - compute an LU factorization, using complete pivoting, of the n-by-n matrix A

SYNOPSIS

       SUBROUTINE ZGETC2( N, A, LDA, IPIV, JPIV, INFO )

	   INTEGER	  INFO, LDA, N

	   INTEGER	  IPIV( * ), JPIV( * )

	   COMPLEX*16	  A( LDA, * )

PURPOSE

       ZGETC2  computes  an  LU  factorization, using complete pivoting, of the n-by-n matrix A. The factorization has the form A = P * L * U * Q,
       where P and Q are permutation matrices, L is lower triangular with unit diagonal elements and U is upper triangular.

       This is a level 1 BLAS version of the algorithm.

ARGUMENTS

       N       (input) INTEGER
	       The order of the matrix A. N >= 0.

       A       (input/output) COMPLEX*16 array, dimension (LDA, N)
	       On entry, the n-by-n matrix to be factored.  On exit, the factors L and U from the factorization A =  P*L*U*Q;  the  unit  diagonal
	       elements  of  L	are not stored.  If U(k, k) appears to be less than SMIN, U(k, k) is given the value of SMIN, giving a nonsingular
	       perturbed system.

       LDA     (input) INTEGER
	       The leading dimension of the array A.  LDA >= max(1, N).

       IPIV    (output) INTEGER array, dimension (N).
	       The pivot indices; for 1 <= i <= N, row i of the matrix has been interchanged with row IPIV(i).

       JPIV    (output) INTEGER array, dimension (N).
	       The pivot indices; for 1 <= j <= N, column j of the matrix has been interchanged with column JPIV(j).

       INFO    (output) INTEGER
	       = 0: successful exit
	       > 0: if INFO = k, U(k, k) is likely to produce overflow if one tries to solve for x in Ax = b. So U is perturbed to avoid the over-
	       flow.

FURTHER DETAILS

       Based on contributions by
	  Bo Kagstrom and Peter Poromaa, Department of Computing Science,
	  Umea University, S-901 87 Umea, Sweden.

LAPACK version 3.0						   15 June 2000 							 ZGETC2(l)