
ZGETC2(l) ) ZGETC2(l)
NAME
ZGETC2  compute an LU factorization, using complete pivoting, of the nbyn 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 nbyn 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 nbyn 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 overflow.
FURTHER DETAILS
Based on contributions by
Bo Kagstrom and Peter Poromaa, Department of Computing Science,
Umea University, S901 87 Umea, Sweden.
LAPACK version 3.0 15 June 2000 ZGETC2(l) 
