DLANSY(3)

💖 DLANSY(3) — the real-symmetric-matrix norm queen 👑

Manual name: DLANSY(3), living under Library Functions Manual, and the header points at /home/abui...RC/dlansy.f(3). Bestie, this page is all about a double precision function that returns a norm of a real symmetric matrix. Iconic behavior. ✨

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🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dlansy.f — that's the file this page is serving, no cap. 💅

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✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

• double precision function DLANSY (norm, uplo, n, a, lda, work) — DLANSY returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric matrix.

double precision function DLANSY (norm, uplo, n, a, lda, work)

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👑 Function/Subroutine Documentation 👑

🎀 double precision function DLANSY 🎀

   double precision function DLANSY (character norm, character uplo, integer n,
       double precision, dimension( lda, * ) a, integer lda, double precision,
       dimension( * ) work)

DLANSY returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a real symmetric matrix. That's the whole assignment, and it ate. 💖

💫 Purpose 💫

!>
!> DLANSY  returns the value of the one norm,  or the Frobenius norm, or
!> the  infinity norm,  or the  element of  largest absolute value  of a
!> real symmetric matrix A.
!>

🌈 Returns 🌈

!>
!>    DLANSY = ( max(abs(A(i,j))), NORM = 'M' or 'm'
!>             (
!>             ( norm1(A),         NORM = '1', 'O' or 'o'
!>             (
!>             ( normI(A),         NORM = 'I' or 'i'
!>             (
!>             ( normF(A),         NORM = 'F', 'f', 'E' or 'e'
!>
!> where  norm1  denotes the  one norm of a matrix (maximum column sum),
!> normI  denotes the  infinity norm  of a matrix  (maximum row sum) and
!> normF  denotes the  Frobenius norm of a matrix (square root of sum of
!> squares).  Note that  max(abs(A(i,j)))  is not a consistent matrix norm.
!>

Read that carefully, bestie: max(abs(A(i,j))) is not a consistent matrix norm. The manual said it, so we're saying it. 🫶

🧸 Parameters 🧸

• NORM — NORM is CHARACTER*1. It specifies the value to be returned in DLANSY as described above. Basically the vibe selector. ✨
• UPLO — UPLO is CHARACTER*1. It specifies whether the upper or lower triangular part of the symmetric matrix A is to be referenced.
  • = 'U': Upper triangular part of A is referenced
  • = 'L': Lower triangular part of A is referenced
• N — N is INTEGER. The order of the matrix A. N >= 0. When N = 0, DLANSY is set to zero. Zero case handled, periodt. 💅
• A — A is DOUBLE PRECISION array, dimension (LDA,N). The symmetric matrix A. If UPLO = 'U', the leading n by n upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading n by n lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced. She only reads the half you told her to read. 🦋
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(N,1). Respect the leading dimension or catch these hands. 😭
• WORK — WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)), where LWORK >= N when NORM = 'I' or '1' or 'O'; otherwise, WORK is not referenced. Sometimes she's needed, sometimes she's simply not referenced. 🍓

🌟 Author 🌟

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

Definition at line 121 of file dlansy.f.

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🦋 Author 🦋

Generated automatically by Doxygen for LAPACK from the source code.

Okay bestie, that's the whole page 💖 — source/version: LAPACK Version 3.12.0; footer path: /home/abui...RC/dlansy.f(3). Every flag, parameter, return, author, and line number is here. No details were left on read. 👑✨