SRC/zhetrf_aa.f(3)

💅 NAME 💅

This is the Library Functions Manual page for SRC/zhetrf_aa.f, bestie — manual name folded in right at the top. ✨

🌸 SYNOPSIS 🌸

🎀 Functions/Subroutines 🎀

       subroutine zhetrf_aa (uplo, n, a, lda, ipiv, work, lwork, info)
           ZHETRF_AA

🦋 FUNCTION/SUBROUTINE DOCUMENTATION 🦋

   subroutine zhetrf_aa (character uplo, integer n, complex*16, dimension( lda,
       * ) a, integer lda, integer, dimension( * ) ipiv, complex*16, dimension(
       * ) work, integer lwork, integer info)
       ZHETRF_AA

✨ Purpose ✨

Okay so ZHETRF_AA computes the factorization of a complex hermitian matrix A using Aasen's algorithm. The form of the factorization is:

A = U**H*T*U  or  A = L*T*L**H

where U (or L) is a product of permutation and unit upper (lower) triangular matrices, and T is a hermitian tridiagonal matrix. 💖

This is the blocked version of the algorithm, calling Level 3 BLAS. Periodt. 🔥

🎀 Parameters 🎀

• UPLO — CHARACTER*1.
  • = 'U': Upper triangle of A is stored.
  • = 'L': Lower triangle of A is stored.
• N — INTEGER. The order of the matrix A. N >= 0.
• A — COMPLEX*16 array, dimension (LDA,N). On entry, the hermitian matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced. On exit, the tridiagonal matrix is stored in the diagonals and the subdiagonals of A just below (or above) the diagonals, and L is stored below (or above) the subdiagonals, when UPLO is 'L' (or 'U').
• LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• IPIV — INTEGER array, dimension (N). On exit, it contains the details of the interchanges, i.e., the row and column k of A were interchanged with the row and column IPIV(k).
• WORK — COMPLEX*16 array, dimension (MAX(1,LWORK)). On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
• LWORK — INTEGER. The length of WORK. LWORK >= 1, if N >= 1, and LWORK >= 2*N, otherwise. For optimum performance LWORK >= N*(1+NB), where NB is the optimal blocksize, returned by ILAENV. If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.
• INFO — INTEGER.
  • = 0: successful exit.
  • < 0: if INFO = -i, the i-th argument had an illegal value.

💖 Author 💖

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

Definition at line 133 of file zhetrf_aa.f. 📍

🖋️ Author 🖋️

Generated automatically by Doxygen for LAPACK from the source code. 🌈

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Catch you later, bestie! 💅 This page is from LAPACK Version 3.12.0, source SRC/zhetrf_aa.f(3) — now go slay that hermitian factorization. ✨👑