SLAVSP(3)

💅 SLAVSP(3) — the girlies' guide to slavsp.f

ok so first things first, the manual name is slavsp.f(3) and she lives in Library Functions Manual. Her full home address is literally:

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

like she's got a whole government name, we love a documented queen 🎀

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✨ NAME ✨

SLAVSP — she's the one who does the matrix-vector multiply after SSPTRF has already done the factorization. bestie she is the follow-up act 💅

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🌸 SYNOPSIS 🌸

Functions/Subroutines

• subroutine SLAVSP (uplo, trans, diag, n, nrhs, a, ipiv, b, ldb, info) — the short version, iykyk

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🦋 Function/Subroutine Documentation 🦋

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

SLAVSP

🎀 Purpose 🎀

!> !> SLAVSP 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 SSPTRF. !> !> 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' ) !>

translation bestie: you hand her the packed factor from SSPTRF, she multiplies your vector(s) by it. no cap, that's the whole vibe ✨

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💖 Parameters 💖

• UPLO — ohhh okay so UPLO is CHARACTER*1 and it specifies whether the factor stored in A is upper or lower triangular. pick your fighter:
  • = 'U': Upper triangular 💫
  • = 'L': Lower triangular 🌊

!> UPLO is 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. she's got three moods:
  • = 'N': x := A*x
  • = 'T': x := A'*x
  • = 'C': x := A'*x

!> TRANS is 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. iconic either way:
  • = 'U': Diagonal blocks are assumed to be unit matrices.
  • = 'N': Diagonal blocks are assumed to be non-unit matrices.

!> DIAG is 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. constraint: N >= 0. as she should 🫶

!> N is 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. constraint: NRHS >= 0. multiple besties, multiple vectors, we stan a multitasker 😭

!> NRHS is 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 (N*(N+1)/2). it's the block diagonal matrix D and the multipliers used to obtain the factor U or L, stored as a packed triangular matrix as computed by SSPTRF. packed! she does not waste space, she is lowkey efficient like that 🔥

!> A is REAL array, dimension (N*(N+1)/2) !> The block diagonal matrix D and the multipliers used to !> obtain the factor U or L, stored as a packed triangular !> matrix as computed by SSPTRF. !>

• IPIV — INTEGER array, dimension (N). the pivot indices from SSPTRF. keep 'em, you'll need 'em.

!> IPIV is INTEGER array, dimension (N) !> The pivot indices from SSPTRF. !>

• 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. 💀 heads up bestie, she will eat your input, that's not a bug that's the design:

!> B is 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. constraint: LDB >= max(1,N). do not skip this one, she will notice 🙈

!> LDB is INTEGER !> The leading dimension of the array B. LDB >= max(1,N). !>

• INFO — INTEGER, the receipts:
  • = 0: successful exit ✨
  • < 0: if INFO = -k, the k-th argument had an illegal value 👀

!> INFO is INTEGER !> = 0: successful exit !> < 0: if INFO = -k, the k-th argument had an illegal value !>

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👑 Author 👑

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

Definition at line 128 of file slavsp.f.

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🌈 Author (again, yes really) 🌈

Generated automatically by Doxygen for LAPACK from the source code. she's auto-generated and she's still main character energy, we love to see it 💜

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🎀 ok that's the whole page, no notes. every flag documented, every constraint honored, periodt.

🌸 signed off with LAPACK, Version 3.12.0, and stamped from /home/abui...IN/slavsp.f(3) — mwah, go multiply something 💋