/home/abui...RC/ssyev.f(3)

🦋 ssyev.f(3) — Library Functions Manual 🦋

Okay bestie, so this is the page for ssyev.f(3), and the manual name is Library Functions Manual. The header line says /home/abui...RC/ssyev.f(3) — that’s the truncated vibe — and the full source path is down in NAME, no cap. ✨

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💖 NAME 💖

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/ssyev.f — yes, that whole long iconic path is the file this page is about. 🫶

🌸 SYNOPSIS 🌸

🧚 Functions/Subroutines 🧚

• subroutine SSYEV (jobz, uplo, n, a, lda, w, work, lwork, info) — SSYEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for SY matrices

🎀 Function/Subroutine Documentation 🎀

🌟 subroutine SSYEV 🌟

subroutine SSYEV (character jobz, character uplo, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( * ) w, real, dimension( * ) work, integer lwork, integer info)

SSYEV computes the eigenvalues and, optionally, the left and/or right eigenvectors for SY matrices. 💅

🦋 Purpose 🦋

Literally the whole point: SSYEV computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A. The source comment is giving !> energy, so here it is raw and untouched:

!>
!> SSYEV computes all eigenvalues and, optionally, eigenvectors of a
!> real symmetric matrix A.
!>

🍓 Parameters 🍓

• JOBZ — JOBZ is CHARACTER*1
  • = 'N': Compute eigenvalues only;
  • = 'V': Compute eigenvalues and eigenvectors.
• UPLO — UPLO is CHARACTER*1
  • = 'U': Upper triangle of A is stored;
  • = 'L': Lower triangle of A is stored.
• 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. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A.
  • On exit, if JOBZ = 'V', then if INFO = 0, A contains the orthonormal eigenvectors of the matrix A.
  • If JOBZ = 'N', then on exit the lower triangle (if UPLO='L') or the upper triangle (if UPLO='U') of A, including the diagonal, is destroyed.

⚠️ Bestie, that last part is not a drill: with JOBZ = 'N', that triangle of A gets destroyed, diagonal included. Like, gone-gone. 💀

• LDA — LDA is INTEGER
  • The leading dimension of the array A. LDA >= max(1,N). 📏
• W — W is REAL array, dimension (N)
  • If INFO = 0, the eigenvalues in ascending order. 🌈
• WORK — WORK is REAL array, dimension (MAX(1,LWORK))
  • On exit, if INFO = 0, WORK(1) returns the optimal LWORK. ✨
• LWORK — LWORK is INTEGER
  • The length of the array WORK. LWORK >= max(1,3*N-1).
  • For optimal efficiency, LWORK >= (NB+2)*N, where NB is the blocksize for SSYTRD returned by ILAENV.
  • If LWORK = -1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA. 🫡
• INFO — INFO is INTEGER
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value
  • > 0: if INFO = i, the algorithm failed to converge; i off-diagonal elements of an intermediate tridiagonal form did not converge to zero.

😭 If INFO > 0, the algorithm did not converge, and i off-diagonal elements of an intermediate tridiagonal form did not converge to zero. That’s the “it’s giving instability” warning, fr fr.

👑 Author 👑

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

📍 Definition 📍

Definition at line 131 of file ssyev.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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Okay bestie, that’s the whole page. Source/version: LAPACK Version 3.12.0. Footer path: /home/abui...RC/ssyev.f(3) — and no separate calendar date is shown in this copy, so that’s the footer vibe we’re working with. Mwah 💋✨🫶