clahef_aa.f man page




subroutine clahef_aa (UPLO, J1, M, NB, A, LDA, IPIV, H, LDH, WORK)

Function/Subroutine Documentation

subroutine clahef_aa (character UPLO, integer J1, integer M, integer NB, complex, dimension( lda, * ) A, integer LDA, integer, dimension( * ) IPIV, complex, dimension( ldh, * ) H, integer LDH, complex, dimension( * ) WORK)



 CLAHEF_AA factorizes a panel of a complex hermitian matrix A using
 the 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, the 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)-th row, or column, of A (without the unit diagonals), while
 the diagonal and subdiagonal of A are overwritten by those of T.


          UPLO is CHARACTER*1
          = 'U':  Upper triangle of A is stored;
          = 'L':  Lower triangle of A is stored.


          J1 is INTEGER
          The location of the first row, or column, of the panel
          within the submatrix of A, passed to this routine, e.g.,
          when called by CHETRF_AA, for the first panel, J1 is 1,
          while for the remaining panels, J1 is 2.


          M is INTEGER
          The dimension of the submatrix. M >= 0.


          NB is INTEGER
          The dimension of the panel to be facotorized.


          A is COMPLEX array, dimension (LDA,M) for
          the first panel, while dimension (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.

          On exit, the leading panel is factorized.


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


          IPIV is INTEGER array, dimension (N)
          Details of the row and column interchanges,
          the row and column k were interchanged with the row and
          column IPIV(k).


          H is COMPLEX workspace, dimension (LDH,NB).


          LDH is INTEGER
          The leading dimension of the workspace H. LDH >= max(1,M).


          WORK is COMPLEX workspace, dimension (M).

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NAG Ltd.


November 2017

Definition at line 146 of file clahef_aa.f.


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Referenced By

The man page clahef_aa(3) is an alias of clahef_aa.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK