TESTING/LIN/slavsp.f(3)

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version 3.12.1 · 3 versions
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💅 TESTING/LIN/slavsp.f(3) 💅

okay so this page is from the Library Functions Manual — yes bestie, that manual name is getting its little cameo near the top so we don’t have to copy the header line, periodt. It’s all about TESTING/LIN/slavsp.f, and the main character is the slavsp routine. ✨

✨ NAME ✨

TESTING/LIN/slavsp.f — that’s the page, and the whole vibe is the slavsp subroutine. no cap. 🎀

🛠️ SYNOPSIS 🛠️

Functions/Subroutines

  • subroutine slavsp (uplo, trans, diag, n, nrhs, a, ipiv, b, ldb, info) — SLAVSP

🌸 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 💖

okay bestie, SLAVSP performs one of the matrix-vector operations

  • x := A*x
  • 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.

The TRANS tea is giving:

  • 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

UPLO is CHARACTER*1 and specifies whether the factor stored in A is upper or lower triangular.

  • 'U': Upper triangular
  • 'L': Lower triangular

TRANS

TRANS is CHARACTER*1 and specifies the operation to be performed:

  • 'N': x := A*x
  • 'T': x := A'*x
  • 'C': x := A'*x

DIAG

DIAG is CHARACTER*1 and 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

N is INTEGER — the number of rows and columns of the matrix A. N >= 0.

NRHS

NRHS is INTEGER — the number of right hand sides, i.e., the number of vectors x to be multiplied by A. NRHS >= 0.

A

A is 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.

IPIV

IPIV is INTEGER array, dimension (N).

These are the pivot indices from SSPTRF.

B

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

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

INFO

INFO is 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 128 of file slavsp.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

💖 that’s the whole page, bestie — source/version is LAPACK, Version 3.12.0, and the footer’s date/page stamp is TESTING/LIN/slavsp.f(3). Go slay your packed triangular matrix math! 💅✨

📦 where this page comes from