SRC/dlansy.f(3)

💖 NAME 💖

okay so this is the page for SRC/dlansy.f, and yes bestie, it’s from the Library Functions Manual — folded in right here like a little name tag 🫶. We’re talking about dlansy, a double precision function with main-character norm energy.

✨ 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.

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🦋 Function/Subroutine Documentation 🦋

🩷 the full signature, exactly as it is

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

The long-form glow-up is literally the same promise: 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. Periodt. 💅

💜 Purpose 💜

DLANSY is here to hand you the one norm, the Frobenius norm, the infinity norm, or the element of largest absolute value of a real symmetric matrix A. That’s the vibe, that’s the job, no cap. ✨

🎀 Returns 🎀

The return value is literally called DLANSY, and here’s the exact norm menu from the source — do not lose a single character of it, bestie:

!>
!>    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.
!>

💅 Parameters 💅

Every single parameter is important here, so let’s give them all their moment. 🌸

• NORM — NORM is CHARACTER*1. It specifies the value to be returned in DLANSY as described above, aka the norm-menu situation from Returns. 🍓
• 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. Iconic zero behavior, honestly. 💀
• A — A is DOUBLE PRECISION array, dimension (LDA,N). This is 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.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(N,1). Respect the leading dimension, bestie. 🫶
• 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. That’s the whole work-array tea. ☕

👑 Author 👑

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

Definition at line 121 of file dlansy.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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that’s the whole page, bestie 💖 this little artifact is from LAPACK, Version 3.12.0, for SRC/dlansy.f(3) — auto-generated by Doxygen from the source code, and served with maximum sparkle. periodt. 🌈✨