/home/abui...vsy_rook.f(3)

🎀 NAME 🎀

okay bestie, this is the manual page for /home/abui...vsy_rook.f(3) — it’s giving Library Functions Manual main character energy ✨ and the actual NAME entry is literally this path:

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

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✨ SYNOPSIS ✨

Functions/Subroutines

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

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🦋 Function/Subroutine Documentation 🦋

here’s the full signature, copied with love and zero edits 💅

subroutine SLAVSY_ROOK (character uplo, character trans, character diag,
    integer n, integer nrhs, real, dimension( lda, * ) a, integer lda,
    integer, dimension( * ) ipiv, real, dimension( ldb, * ) b, integer ldb,
    integer info)

SLAVSY_ROOK

🌸 Purpose 🌸

SLAVSY_ROOK performs one of the 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 SSYTRF_ROOK. 🫶

the rules are literally:

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

💖 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, = 'C': 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 — REAL array, dimension (LDA,N). The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF_ROOK. 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 SSYTRF_ROOK.
  • 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) < 0 and IPIV(k-1) < 0, then rows and columns k and -IPIV(k) were interchanged and rows and columns k-1 and -IPIV(k-1) were inerchaged, 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) < 0 and IPIV(k+1) < 0, then rows and columns k and -IPIV(k) were interchanged and rows and columns k+1 and -IPIV(k+1) were inerchaged, D(k:k+1,k:k+1) is a 2-by-2 diagonal block.
• B — REAL 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 155 of file slavsy_rook.f.

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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