Visible to Intel only — GUID: GUID-210D2C29-E2D2-40B9-8D16-495AC97F11CB
Visible to Intel only — GUID: GUID-210D2C29-E2D2-40B9-8D16-495AC97F11CB
?getc2
Computes the LU factorization with complete pivoting of the general n-by-n matrix.
Syntax
call sgetc2( n, a, lda, ipiv, jpiv, info )
call dgetc2( n, a, lda, ipiv, jpiv, info )
call cgetc2( n, a, lda, ipiv, jpiv, info )
call zgetc2( n, a, lda, ipiv, jpiv, info )
Include Files
- mkl.fi
Description
The routine 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.
The LU factorization computed by this routine is used by ?latdf to compute a contribution to the reciprocal Dif-estimate.
Input Parameters
- n
-
INTEGER. The order of the matrix A (n≥ 0).
- a
-
REAL for sgetc2
DOUBLE PRECISION for dgetc2
COMPLEX for cgetc2
DOUBLE COMPLEX for zgetc2.
Array a(lda,*) contains the n-by-n matrix A to be factored. The second dimension of a must be at least max(1, n);
- lda
-
INTEGER. The leading dimension of a; at least max(1, n).
Output Parameters
- a
-
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, that is giving a nonsingular perturbed system.
- ipiv
-
INTEGER.
Array, DIMENSION at least max(1,n).
The pivot indices: for 1 ≤ i ≤ n, row i of the matrix has been interchanged with row ipiv(i).
- jpiv
-
INTEGER.
Array, DIMENSION at least max(1,n).
The pivot indices: for 1 ≤ j ≤ n, column j of the matrix has been interchanged with column jpiv(j).
- info
-
INTEGER.
If info = 0, the execution is successful.
If info = k>0, U(k, k) is likely to produce overflow if we try to solve for x in A*x = b. So U is perturbed to avoid the overflow.