1ZGETC2(1)           LAPACK auxiliary routine (version 3.1)           ZGETC2(1)
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NAME

6       ZGETC2  -  an  LU factorization, using complete pivoting, of the n-by-n
7       matrix A
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SYNOPSIS

10       SUBROUTINE ZGETC2( N, A, LDA, IPIV, JPIV, INFO )
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12           INTEGER        INFO, LDA, N
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14           INTEGER        IPIV( * ), JPIV( * )
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16           COMPLEX*16     A( LDA, * )
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PURPOSE

19       ZGETC2 computes an LU factorization, using complete pivoting, of the n-
20       by-n  matrix A. The factorization has the form A = P * L * U * Q, where
21       P and Q are permutation matrices, L is lower triangular with unit diag‐
22       onal elements and U is upper triangular.
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24       This is a level 1 BLAS version of the algorithm.
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ARGUMENTS

28       N       (input) INTEGER
29               The order of the matrix A. N >= 0.
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31       A       (input/output) COMPLEX*16 array, dimension (LDA, N)
32               On  entry, the n-by-n matrix to be factored.  On exit, the fac‐
33               tors L and U from the factorization A = P*L*U*Q; the unit diag‐
34               onal  elements  of  L are not stored.  If U(k, k) appears to be
35               less than SMIN, U(k, k) is given the value of  SMIN,  giving  a
36               nonsingular perturbed system.
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38       LDA     (input) INTEGER
39               The leading dimension of the array A.  LDA >= max(1, N).
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41       IPIV    (output) INTEGER array, dimension (N).
42               The  pivot  indices;  for  1 <= i <= N, row i of the matrix has
43               been interchanged with row IPIV(i).
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45       JPIV    (output) INTEGER array, dimension (N).
46               The pivot indices; for 1 <= j <= N, column j of the matrix  has
47               been interchanged with column JPIV(j).
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49       INFO    (output) INTEGER
50               = 0: successful exit
51               >  0: if INFO = k, U(k, k) is likely to produce overflow if one
52               tries to solve for x in Ax = b. So U is perturbed to avoid  the
53               overflow.
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FURTHER DETAILS

56       Based on contributions by
57          Bo Kagstrom and Peter Poromaa, Department of Computing Science,
58          Umea University, S-901 87 Umea, Sweden.
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63 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       ZGETC2(1)
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