SRC/slaqsy.f(3)

🌸 NAME 🌸

Okay bestie, this page is SRC/slaqsy.f, and it lives in the Library Functions Manual — iconic placement, no cap. 💖

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✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

subroutine slaqsy (uplo, n, a, lda, s, scond, amax, equed)

• What it does: SLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ. Slay.

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🔥 Function/Subroutine Documentation 🔥

🦋 subroutine slaqsy (character uplo, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( * ) s, real scond, real amax, character equed)

SLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ. Main character energy for real. ✨

🎀 Purpose:

SLAQSY equilibrates a symmetric matrix A using the scaling factors in the vector S. Literally its whole job. 💅

💅 Parameters

• UPLO — UPLO is CHARACTER*1. It specifies whether the upper or lower triangular part of the symmetric matrix A is stored.
  • = 'U': Upper triangular
  • = 'L': Lower triangular
• N — N is INTEGER. The order of the matrix A. N >= 0.
• A — A is REAL 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 — LDA is INTEGER. The leading dimension of the array A. LDA >= max(N,1).
• S — S is REAL array, dimension (N). The scale factors for A.
• SCOND — SCOND is REAL. Ratio of the smallest S(i) to the largest S(i).
• AMAX — AMAX is REAL. Absolute value of largest matrix entry.
• EQUED — 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  • = 'Y': Equilibration was done, i.e., A has been replaced by diag(S) * A * diag(S).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 at line 132 of file slaqsy.f.

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📝 Author

Generated automatically by Doxygen for LAPACK from the source code.

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💖 That’s the whole page, bestie — footer vibe: LAPACK, Version 3.12.0, page SRC/slaqsy.f(3). Periodt. 💅