DLAQZ2(3)

💖 NAME 💖

okay so bestie, this page is for /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dlaqz2.f — and yes, it’s from the Library Functions Manual (folding that in right here so we don’t copy the header line, periodt 💅).

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✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

subroutine DLAQZ2 (ilq, ilz, k, istartm, istopm, ihi, a, lda, b, ldb,
    nq, qstart, q, ldq, nz, zstart, z, ldz)

DLAQZ2

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🛠️ Function/Subroutine Documentation 🛠️

subroutine DLAQZ2 (logical, intent(in) ilq, logical, intent(in) ilz,
    integer, intent(in) k, integer, intent(in) istartm, integer, intent(in)
    istopm, integer, intent(in) ihi, double precision, dimension( lda, * )
    a, integer, intent(in) lda, double precision, dimension( ldb, * ) b,
    integer, intent(in) ldb, integer, intent(in) nq, integer, intent(in)
    qstart, double precision, dimension( ldq, * ) q, integer, intent(in)
    ldq, integer, intent(in) nz, integer, intent(in) zstart, double
    precision, dimension( ldz,                          * ) z, integer,
    intent(in) ldz)

DLAQZ2

🎯 Purpose 🎯

DLAQZ2 chases a 2x2 shift bulge in a matrix pencil down a single position. That’s the whole vibe of this one, no cap 🦋.

🧸 Parameters 🧸

• ILQ — ILQ is LOGICAL. It determines whether or not to update the matrix Q.
• ILZ — ILZ is LOGICAL. It determines whether or not to update the matrix Z.
• K — K is INTEGER. Index indicating the position of the bulge. On entry, the bulge is located in (A(k+1:k+2,k:k+1),B(k+1:k+2,k:k+1)). On exit, the bulge is located in (A(k+2:k+3,k+1:k+2),B(k+2:k+3,k+1:k+2)).
• ISTARTM — ISTARTM is INTEGER. That’s literally the description, bestie — no extra lore here 💀.
• ISTOPM — ISTOPM is INTEGER. Updates to (A,B) are restricted to (istartm:k+3,k:istopm). It is assumed without checking that istartm <= k+1 and k+2 <= istopm.
• IHI — IHI is INTEGER. Again, that’s the whole description. Short and iconic.
• A — A is DOUBLE PRECISION array, dimension (LDA,N).
• LDA — LDA is INTEGER. The leading dimension of A as declared in the calling procedure.
• B — B is DOUBLE PRECISION array, dimension (LDB,N).
• LDB — LDB is INTEGER. The leading dimension of B as declared in the calling procedure.
• NQ — NQ is INTEGER. The order of the matrix Q.
• QSTART — QSTART is INTEGER. Start index of the matrix Q. Rotations are applied to columns k+2-qStart:k+4-qStart of Q.
• Q — Q is DOUBLE PRECISION array, dimension (LDQ,NQ).
• LDQ — LDQ is INTEGER. The leading dimension of Q as declared in the calling procedure.
• NZ — NZ is INTEGER. The order of the matrix Z.
• ZSTART — ZSTART is INTEGER. Start index of the matrix Z. Rotations are applied to columns k+1-qStart:k+3-qStart of Z.
• Z — Z is DOUBLE PRECISION array, dimension (LDZ,NZ).
• LDZ — LDZ is INTEGER. The leading dimension of Q as declared in the calling procedure. (Yep, it says Q right there — I’m just the messenger 💅.)

🫶 Author 🫶

Thijs Steel, KU Leuven

📅 Date 📅

May 2020

Definition at line 172 of file dlaqz2.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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okay that’s the whole page, bestie — LAPACK Version 3.12.0, date May 2020, footer path /home/abui...RC/dlaqz2.f(3). bye and slay 💖✨🎀