SRC/zlaqz3.f(3)

💖 NAME 💖

okay bestie, welcome to the SRC/zlaqz3.f page from the Library Functions Manual — that's the manual name, folded in right here so you're oriented. The name on the tin is SRC/zlaqz3.f. Concise queen, lowkey a whole vibe. 🎀

✨ SYNOPSIS ✨

Functions/Subroutines

subroutine zlaqz3 (ilschur, ilq, ilz, n, ilo, ihi, nshifts,
           nblock_desired, alpha, beta, a, lda, b, ldb, q, ldq, z, ldz, qc,
           ldqc, zc, ldzc, work, lwork, info)

ZLAQZ3 — that's the subroutine, periodt. It's giving iconic, and she's highkey the main event. 💅

🦋 Function/Subroutine Documentation 🦋

subroutine zlaqz3

subroutine zlaqz3 (logical, intent(in) ilschur, logical, intent(in) ilq,
       logical, intent(in) ilz, integer, intent(in) n, integer, intent(in) ilo,
       integer, intent(in) ihi, integer, intent(in) nshifts, integer,
       intent(in) nblock_desired, complex*16, dimension( * ), intent(inout)
       alpha, complex*16, dimension( * ), intent(inout) beta, complex*16,
       dimension( lda, * ), intent(inout) a, integer, intent(in) lda,
       complex*16, dimension( ldb, * ), intent(inout) b, integer, intent(in)
       ldb, complex*16, dimension( ldq,         * ), intent(inout) q, integer,
       intent(in) ldq, complex*16, dimension( ldz, * ), intent(inout) z,
       integer, intent(in) ldz, complex*16, dimension( ldqc, * ), intent(inout)
       qc, integer, intent(in) ldqc, complex*16, dimension( ldzc, * ),
       intent(inout) zc, integer, intent(in) ldzc, complex*16, dimension( * ),
       intent(inout) work, integer, intent(in) lwork, integer, intent(out)
       info)

ZLAQZ3 — yes, the name shows up again, and honestly? Main character energy. 👑

Purpose

The purpose is literally: ZLAQZ3 Executes a single multishift QZ sweep. That's the whole assignment, no cap. She ate. 🔥

Parameters

Vibe check: every parameter is here, no skips, no cuts — ngl, let's get into it:

• ILSCHUR — ILSCHUR is LOGICAL. Determines whether or not to update the full Schur form.
• ILQ — ILQ is LOGICAL. Determines whether or not to update the matrix Q.
• ILZ — ILZ is LOGICAL. Determines whether or not to update the matrix Z.
• N — N is INTEGER. The order of the matrices A, B, Q, and Z. N >= 0.
• ILO — ILO is INTEGER.
• IHI — IHI is INTEGER.
• NSHIFTS — NSHIFTS is INTEGER. The desired number of shifts to use.
• NBLOCK_DESIRED — NBLOCK_DESIRED is INTEGER. The desired size of the computational windows.
• ALPHA — ALPHA is COMPLEX*16 array. SR contains the alpha parts of the shifts to use.
• BETA — BETA is COMPLEX*16 array. SS contains the scale of the shifts to use.
• A — A is COMPLEX*16 array, dimension (LDA, N).
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max( 1, N ).
• B — B is COMPLEX*16 array, dimension (LDB, N).
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max( 1, N ).
• Q — Q is COMPLEX*16 array, dimension (LDQ, N).
• LDQ — LDQ is INTEGER.
• Z — Z is COMPLEX*16 array, dimension (LDZ, N).
• LDZ — LDZ is INTEGER.
• QC — QC is COMPLEX*16 array, dimension (LDQC, NBLOCK_DESIRED).
• LDQC — LDQC is INTEGER.
• ZC — ZC is COMPLEX*16 array, dimension (LDZC, NBLOCK_DESIRED).
• LDZC — LDZ is INTEGER. yes bestie, the page literally says LDZ here; I'm not fixing it, I'm preserving the lore 😭
• WORK — WORK is COMPLEX*16 array, dimension (MAX(1,LWORK)). On exit, if INFO >= 0, WORK(1) returns the optimal LWORK.
• LWORK — LWORK is INTEGER. The dimension of the array WORK. LWORK >= max(1,N).

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

Author

Thijs Steel, KU Leuven — shoutout to the author, obsessed. 💖

Date

May 2020 — a whole era. Noted.

Definition at line 204 of file zlaqz3.f. — she's officially defined there, bestie.

Author

Generated automatically by Doxygen for LAPACK from the source code. Robots did this one, no cap. 🤖

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okay that's the whole page, bestie 🫶. This little beauty is from LAPACK Version 3.12.0, and the page is SRC/zlaqz3.f(3). Stay slay, and may your workspace queries be as clean as this page. iykyk, fr fr ✨