SRC/dlaqsy.f(3)

SRC/dlaqsy.f(3) is the page title, and the manual name is Library Functions Manual — welcome to the group chat, bestie. This one is all about DLAQSY, and it's literally here to scale a symmetric/Hermitian matrix using scaling factors computed by spoequ. 💅

🌸 NAME 🌸

SRC/dlaqsy.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines

       subroutine dlaqsy (uplo, n, a, lda, s, scond, amax, equed)
           DLAQSY scales a symmetric/Hermitian matrix, using scaling factors
           computed by spoequ.

💅 Function/Subroutine Documentation 💅

   subroutine dlaqsy (character uplo, integer n, double precision, dimension(
       lda, * ) a, integer lda, double precision, dimension( * ) s, double
       precision scond, double precision amax, character equed)
       DLAQSY scales a symmetric/Hermitian matrix, using scaling factors
       computed by spoequ.

DLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ. Iconic behavior, honestly.

🎯 Purpose

DLAQSY equilibrates a symmetric matrix A using the scaling factors in the vector S.

🧾 Parameters

• UPLO — is CHARACTER*1. Specifies whether the upper or lower triangular part of the symmetric matrix A is stored.
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• N — is INTEGER. The order of the matrix A. N >= 0.
• A — is DOUBLE PRECISION array, dimension (LDA,N). On entry, 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.

On exit, if EQUED = 'Y', the equilibrated matrix: diag(S) * A * diag(S).

• LDA — is INTEGER. The leading dimension of the array A. LDA >= max(N,1).
• S — is DOUBLE PRECISION array, dimension (N). The scale factors for A.
• SCOND — is DOUBLE PRECISION. Ratio of the smallest S(i) to the largest S(i).
• AMAX — is DOUBLE PRECISION. Absolute value of largest matrix entry.
• EQUED — is CHARACTER*1. Specifies whether or not equilibration was done.
  • = 'N': No equilibration.
  • = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).

🔮 Internal Parameters

• THRESH is a threshold value used to decide if scaling should be done based on the ratio of the scaling factors. If SCOND < THRESH, scaling is done.
• LARGE and SMALL are threshold values used to decide if scaling should be done based on the absolute size of the largest matrix element. If AMAX > LARGE or AMAX < SMALL, scaling is done.

👑 Author

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

📌 Definition

Definition at line 132 of file dlaqsy.f.

🪄 Author

Generated automatically by Doxygen for LAPACK from the source code.

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💖 Okay that's the whole page, bestie. The footer wraps it up with LAPACK, Version 3.12.0, and SRC/dlaqsy.f(3) — no separate date line in that footer, just those iconic version/source details. Periodt. 🎀