TESTING/LIN/clavsy.f(3)

From TESTING/LIN/clavsy.f(3), Library Functions Manual — okay bestie, this is the LAPACK subroutine page for clavsy, and it’s giving “matrix-vector product main character energy” while being extremely specific about every single argument. 💅✨

💖 NAME 💖

TESTING/LIN/clavsy.f — yes, that’s the whole name section. The file is the moment. 🎀

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

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

CLAVSY

🫶 Function/Subroutine Documentation 🫶

Here’s the full signature, character-for-character, no cap:

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

CLAVSY

🎯 Purpose 🎯

CLAVSY 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 CSYTRF.

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'). Periodt. 💖

🌸 Parameters 🌸

💜 UPLO

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

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

🦋 TRANS

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

• = 'N': x := A*x
• = 'T': x := A'*x

🎀 DIAG

DIAG is CHARACTER*1. It 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. It’s the number of rows and columns of the matrix A. N >= 0.

🌈 NRHS

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

🍓 A

A is COMPLEX array, dimension (LDA,N). It’s the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by CSYTRF. Stored as a 2-D triangular matrix.

🧚 LDA

LDA is INTEGER. It’s the leading dimension of the array A. LDA >= max(1,N).

🔥 IPIV

IPIV is INTEGER array, dimension (N). It holds details of the interchanges and the block structure of D, as determined by CSYTRF.

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

B is COMPLEX 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. It’s 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

Definition at line 151 of file clavsy.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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That’s the page, bestie. Footer vibes: LAPACK, Version 3.12.0, source path TESTING/LIN/clavsy.f(3). The footer doesn’t hand us a date, so no invented calendar tea — just cute Unix fairy dust and a very thorough clavsy moment. 🧚✨🎀