ZLAQZ2(3)

🎀 ZLAQZ2(3) 🎀

okay bestie, welcome to the zlaqz2.f(3) page from the Library Functions Manual — the path situation is /home/abui...RC/zlaqz2.f(3), and it is giving very “LAPACK internals era.” ✨

💖 NAME 💖

The NAME section is literally just the file path, no nickname, no cute little alias:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/zlaqz2.f

That’s it. Iconic minimalism. 🫶

🌸 SYNOPSIS 🌸

🧚 Functions/Subroutines 🧚

Here’s the synopsis signature, exactly:

       recursive subroutine ZLAQZ2 (ilschur, ilq, ilz, n, ilo, ihi, nw, a, lda,
           b, ldb, q, ldq, z, ldz, ns, nd, alpha, beta, qc, ldqc, zc, ldzc,
           work, lwork, rwork, rec, info)
           ZLAQZ2

and then it hits you with ZLAQZ2 again, because why not. 💅

🫶 FUNCTION/SUBROUTINE DOCUMENTATION 🫶

The full typed signature is a whole moment — all the intent(in) / intent(out) / intent(inout) lore is preserved:

   recursive subroutine ZLAQZ2 (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) nw,
       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, integer, intent(out) ns,
       integer, intent(out) nd, complex*16, dimension( * ), intent(inout)
       alpha, complex*16, dimension( * ), intent(inout) beta, complex*16,
       dimension( ldqc, * ) qc, integer, intent(in) ldqc, complex*16,
       dimension( ldzc, * ) zc, integer, intent(in) ldzc, complex*16,
       dimension( * ) work, integer, intent(in) lwork, double precision,
       dimension( * ) rwork, integer, intent(in) rec, integer, intent(out)
       info)
       ZLAQZ2

yes, it says ZLAQZ2 again after the signature. main character energy. 👑

🌟 Purpose 🌟

The Purpose block is short and slay:

!>
!> ZLAQZ2 performs AED
!>

that’s literally it. AED girlies know. 🔥

💜 Parameters 💜

• ILSCHUR — LOGICAL; determines whether or not to update the full Schur form. ✨
• ILQ — LOGICAL; determines whether or not to update the matrix Q.
• ILZ — LOGICAL; determines whether or not to update the matrix Z.
• N — INTEGER; the order of the matrices A, B, Q, and Z. N >= 0.
• ILO — INTEGER. that’s the whole description, bestie.
• IHI — INTEGER; ILO and IHI mark the rows and columns of (A,B) which are to be normalized.
• NW — INTEGER; the desired size of the deflation window.
• A — COMPLEX*16 array, dimension (LDA, N).
• LDA — INTEGER; the leading dimension of the array A. LDA >= max( 1, N ).
• B — COMPLEX*16 array, dimension (LDB, N).
• LDB — INTEGER; the leading dimension of the array B. LDB >= max( 1, N ).
• Q — COMPLEX*16 array, dimension (LDQ, N).
• LDQ — INTEGER.
• Z — COMPLEX*16 array, dimension (LDZ, N).
• LDZ — INTEGER.
• NS — INTEGER; the number of unconverged eigenvalues available to use as shifts.
• ND — INTEGER; the number of converged eigenvalues found.
• ALPHA — COMPLEX*16 array, dimension (N); each scalar alpha defining an eigenvalue of GNEP.
• BETA — COMPLEX*16 array, dimension (N); the scalars beta that define the eigenvalues of GNEP. Together, the quantities alpha = ALPHA(j) and beta = BETA(j) represent the j-th eigenvalue of the matrix pair (A,B), in one of the forms lambda = alpha/beta or mu = beta/alpha. Since either lambda or mu may overflow, they should not, in general, be computed. 😭
• QC — COMPLEX*16 array, dimension (LDQC, NW).
• LDQC — INTEGER.
• ZC — COMPLEX*16 array, dimension (LDZC, NW).
• LDZC — the description literally says LDZ is INTEGER here, under LDZC — yes, that’s what the page says, no cap. 🙈
• WORK — COMPLEX*16 array, dimension (MAX(1,LWORK)). On exit, if INFO >= 0, WORK(1) returns the optimal LWORK.
• LWORK — 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.
• RWORK — DOUBLE PRECISION array, dimension (N).
• REC — INTEGER; REC indicates the current recursion level. Should be set to 0 on first call.
• INFO — INTEGER; = 0: successful exit; < 0: if INFO = -i, the i-th argument had an illegal value.

👑 Author 👑

Thijs Steel, KU Leuven

📅 Date 📅

May 2020

📍 Definition 📍

Definition at line 230 of file zlaqz2.f.

📝 Author 📝

Generated automatically by Doxygen for LAPACK from the source code.

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okay that’s the whole page, bestie. This was LAPACK Version 3.12.0, dated May 2020, living at /home/abui...RC/zlaqz2.f(3) — drink water, don’t let your leading dimensions overflow, mwah 💖✨🦋