ZLAEIN(3)

Okay bestie, welcome to ZLAEIN(3) — yes, the zlaein.f(3) page from the Library Functions Manual 💅. We’re in LAPACK land today, and the main character is ZLAEIN: it computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration. No cap.

💖 NAME 💖

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/zlaein.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

subroutine ZLAEIN (rightv, noinit, n, h, ldh, w, v, b, ldb, rwork, eps3,
    smlnum, info)

ZLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration. Periodt. 💅

🌸 Function/Subroutine Documentation 🌸

subroutine ZLAEIN (logical rightv, logical noinit, integer n, complex*16,
    dimension( ldh, * ) h, integer ldh, complex*16 w, complex*16, dimension(
    * ) v, complex*16, dimension( ldb, * ) b, integer ldb, double precision,
    dimension( * ) rwork, double precision eps3, double precision smlnum,
    integer info)

ZLAEIN computes a specified right or left eigenvector of an upper Hessenberg matrix by inverse iteration. Same iconic behavior, now with the full signature ✨.

🎀 Purpose 🎀

ZLAEIN uses inverse iteration to find a right or left eigenvector corresponding to the eigenvalue W of a complex upper Hessenberg matrix H. That’s the whole plot, bestie. 🦋

🧚 Parameters 🧚

• RIGHTV — RIGHTV is LOGICAL. = .TRUE. : compute right eigenvector; = .FALSE.: compute left eigenvector. Pick your vibe. 💖
• NOINIT — NOINIT is LOGICAL. = .TRUE. : no initial vector supplied in V; = .FALSE.: initial vector supplied in V.
• N — N is INTEGER. The order of the matrix H. N >= 0.
• H — H is COMPLEX*16 array, dimension (LDH,N). The upper Hessenberg matrix H.
• LDH — LDH is INTEGER. The leading dimension of the array H. LDH >= max(1,N).
• W — W is COMPLEX*16. The eigenvalue of H whose corresponding right or left eigenvector is to be computed.
• V — V is COMPLEX*16 array, dimension (N). On entry, if NOINIT = .FALSE., V must contain a starting vector for inverse iteration; otherwise V need not be set. On exit, V contains the computed eigenvector, normalized so that the component of largest magnitude has magnitude 1; here the magnitude of a complex number (x,y) is taken to be |x| + |y|.
• B — B is COMPLEX*16 array, dimension (LDB,N).
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max(1,N).
• RWORK — RWORK is DOUBLE PRECISION array, dimension (N).
• EPS3 — EPS3 is DOUBLE PRECISION. A small machine-dependent value which is used to perturb close eigenvalues, and to replace zero pivots.
• SMLNUM — SMLNUM is DOUBLE PRECISION. A machine-dependent value close to the underflow threshold.
• INFO — INFO is INTEGER. = 0: successful exit. = 1: inverse iteration did not converge; V is set to the last iterate.

👑 Author 👑

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

Definition at line 147 of file zlaein.f.

🦋 Author 🦋

Generated automatically by Doxygen for LAPACK from the source code.

Cute sign-off, bestie: this footer moment is LAPACK Version 3.12.0, with the path /home/abui...RC/zlaein.f(3) — slay, bye! 💖🎀✨