SGETC2 computes an LU factorization with 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 the Level 2 BLAS algorithm.

N

          N is INTEGER


          The order of the matrix A. N >= 0.

A

          A is REAL array, dimension (LDA, N)


          On entry, the n-by-n matrix A 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, i.e., giving a nonsingular perturbed system.

LDA

          LDA is INTEGER


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

IPIV

          IPIV is INTEGER array, dimension(N).


          The pivot indices; for 1 <= i <= N, row i of the


          matrix has been interchanged with row IPIV(i).

JPIV

          JPIV is INTEGER array, dimension(N).


          The pivot indices; for 1 <= j <= N, column j of the


          matrix has been interchanged with column JPIV(j).

INFO

          INFO is INTEGER


           = 0: successful exit


           > 0: if INFO = k, U(k, k) is likely to produce owerflow if


                we try to solve for x in Ax = b. So U is perturbed to


                avoid the overflow.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

September 2012

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