ZLAVSY(3)

💖 ZLAVSY(3) — Library Functions Manual 💖

okay bestie, this is the Library Functions Manual page for ZLAVSY(3), and it’s giving “LAPACK linear algebra subroutine that does exactly one job and does it iconically.” We’re keeping every type, flag, and condition, so you can trust the vibes and the facts. ✨

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/zlavsy.f

🦋 SYNOPSIS 🦋

Functions/Subroutines

subroutine ZLAVSY (uplo, trans, diag, n, nrhs, a, lda, ipiv, b, ldb,
    info)
    ZLAVSY

👑 Function/Subroutine Documentation 👑

Here’s the full signature, bestie — every argument exactly as it appears:

subroutine ZLAVSY (character uplo, character trans, character diag, integer
    n, integer nrhs, complex*16, dimension( lda, * ) a, integer lda,
    integer, dimension( * ) ipiv, complex*16, dimension( ldb, * ) b, integer
    ldb, integer info)
ZLAVSY

✨ Purpose ✨

ZLAVSY performs one of these matrix-vector operations:

x := A*x  or  x := A'*x

where x is an N element vector and A is one of the factors from the block U*D*U' or L*D*L' factorization computed by ZSYTRF.

• If TRANS = 'N', it multiplies by U or U * D (or L or L * D).
• If TRANS = 'T', it multiplies by U' or D * U' (or L' or D * L').

Those are the two operations, periodt. 💅

🌈 Parameters 🌈

• UPLO — CHARACTER*1. Specifies whether the factor stored in A is upper or lower triangular.
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• TRANS — CHARACTER*1. Specifies the operation to be performed:
  • = 'N': x := A*x
  • = 'T': x := A'*x
• DIAG — CHARACTER*1. Specifies whether or not the diagonal blocks are unit matrices. If the diagonal blocks are assumed to be unit, then A = U or A = L, otherwise A = U*D or A = L*D.
  • = 'U': Diagonal blocks are assumed to be unit matrices.
  • = 'N': Diagonal blocks are assumed to be non-unit matrices.
• N — INTEGER. The number of rows and columns of the matrix A. N >= 0.
• NRHS — INTEGER. The number of right hand sides, i.e., the number of vectors x to be multiplied by A. NRHS >= 0.
• A — COMPLEX*16 array, dimension (LDA,N). The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ZSYTRF. Stored as a 2-D triangular matrix.
• LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• IPIV — INTEGER array, dimension (N). Details of the interchanges and the block structure of D, as determined by ZSYTRF.
  • If UPLO = 'U':
    • If IPIV(k) > 0, then rows and columns k and IPIV(k) were interchanged and D(k,k) is a 1-by-1 diagonal block. (If IPIV( k ) = k, no interchange was done).
    • If IPIV(k) = IPIV(k-1) < 0, then rows and columns k-1 and -IPIV(k) were interchanged, D(k-1:k,k-1:k) is a 2-by-2 diagonal block.
  • If UPLO = 'L':
    • If IPIV(k) > 0, then rows and columns k and IPIV(k) were interchanged and D(k,k) is a 1-by-1 diagonal block. (If IPIV( k ) = k, no interchange was done).
    • If IPIV(k) = IPIV(k+1) < 0, then rows and columns k+1 and -IPIV(k) were interchanged, D(k:k+1,k:k+1) is a 2-by-2 diagonal block.
• B — COMPLEX*16 array, dimension (LDB,NRHS). On entry, B contains NRHS vectors of length N. On exit, B is overwritten with the product A * B.
• LDB — INTEGER. The leading dimension of the array B. LDB >= max(1,N).
• INFO — INTEGER.
  • = 0: successful exit
  • < 0: if INFO = -k, the k-th argument had an illegal value

💜 Author 💜

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

Definition at line 151 of file zlavsy.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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And that’s the whole page, bestie — LAPACK Version 3.12.0, living at /home/abui...IN/zlavsy.f(3). Slay, and may your arguments always be legal. 🫶💖