Visible to Intel only — GUID: GUID-55DCF8F5-3610-498D-8473-20A625E5AC3A
Visible to Intel only — GUID: GUID-55DCF8F5-3610-498D-8473-20A625E5AC3A
?lahef_aa
Factorizes a panel of a complex Hermitian matrix A using Aasen's algorithm.
call clahef_aa(uplo, j1, m, nb, a, lda, ipiv, h, ldh, work)
call zlahef_aa(uplo, j1, m, nb, a, lda, ipiv, h, ldh, work)
Description
?lahef_aa factorizes a panel of a complex Hermitian matrix A using Aasen's algorithm. The panel consists of a set of nb rows of A when uplo is 'U', or a set of nb columns when uplo is 'L'. In order to factorize the panel, Aasen's algorithm requires the last row, or column, of the previous panel. The first row, or column, of A is set to be the first row, or column, of an identity matrix, which is used to factorize the first panel. The resulting j-th row of U, or j-th column of L, is stored in the (j-1)-st row, or column, of A (without the unit diagonals), while the diagonal and subdiagonal of A are overwritten by those of T.
Input Parameters
- uplo
-
CHARACTER*1.
If uplo = 'U': Upper triangular of A is stored.
If uplo= 'L': Lower triangular of A is stored..
- j1
-
INTEGER. The location of the first row, or column, of the panel within the submatrix of A, passed to this routine, for example when called by ?hetrf_aa. For the first panel, j1 is 1, while for the remaining panels, j1 is 2.
- m
-
INTEGER. The dimension of the submatrix. m≥ 0.
- nb
-
INTEGER. The dimension of the panel to be factorized.
- a
-
COMPLEX for clahef_aa
COMPLEX*16 for zlahef_aa
Array of size (lda,m) for the first panel, and size (lda,m+1) for the remaining panels. On entry, a contains the last row, or column, of the previous panel, and the trailing submatrix of A to be factorized, except for the first panel, only the panel is passed.
- lda
-
INTEGER. The leading dimension of the array a. lda≥ max(1, n).
- h
-
COMPLEX for clahef_aa
COMPLEX*16 for zlahef_aa
Workspace array of size (ldh, nb).
- ldh
-
INTEGER. The leading dimension of the workspace h. ldh≥ max(1,m).
Output Parameters
- a
-
On exit, the leading panel is factorized.
- ipiv
-
INTEGER . Array of size (n). Details of the row and column interchanges: the row and column k were interchanged with the row and column ipiv(k).
- h
-
Workspace array.
- work
-
COMPLEX for clahef_aa
COMPLEX*16 for zlahef_aa
Workspace array of size (m).