SRC/claqz1.f(3)

💅 SRC/claqz1.f — from the LAPACK Library Functions Manual, bestie 🎀

okay so. this is a Fortran subroutine page, it lives in the Library Functions Manual, and it's about chasing a lil bulge around a matrix pencil. yes really. stay with me 💖

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✨ NAME ✨

SRC/claqz1.f — the file. that's it. that's the name. iconic minimalism honestly 💅

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🌸 SYNOPSIS 🌸

Functions/Subroutines

subroutine claqz1 (ilq, ilz, k, istartm, istopm, ihi, a, lda, b, ldb,
    nq, qstart, q, ldq, nz, zstart, z, ldz)

CLAQZ1 🦋

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👑 Function/Subroutine Documentation 👑

subroutine claqz1 (logical, intent(in) ilq, logical, intent(in) ilz,
    integer, intent(in) k, integer, intent(in) istartm, integer, intent(in)
    istopm, integer, intent(in) ihi, complex, dimension( lda, * ) a,
    integer, intent(in) lda, complex, dimension( ldb, * ) b, integer,
    intent(in) ldb, integer, intent(in) nq, integer, intent(in) qstart,
    complex, dimension( ldq, * ) q, integer, intent(in) ldq, integer,
    intent(in) nz, integer, intent(in) zstart, complex, dimension( ldz, * )
    z, integer, intent(in) ldz)

CLAQZ1 ✨ (yes it says it twice, that's just how the page do 💀)

🎯 Purpose

!> !> CLAQZ1 chases a 1x1 shift bulge in a matrix pencil down a single position !>

like literally it takes that one little 1x1 bulge and walks it down exactly one spot. one. single. position. she's not doing cardio, she's doing one step 😌

🌈 Parameters

• ILQ — ILQ is LOGICAL. this one decides whether or not we update the matrix Q. that's the whole job 🫶
• ILZ — ILZ is LOGICAL. same energy, but for the matrix Z. determines whether or not to update it 💜
• K — K is INTEGER. the index that says where the bulge is chilling.
  • on entry, the bulge is located in (A(k+1,k),B(k+1,k)). 📍
  • on exit, the bulge is located in (A(k+2,k+1),B(k+2,k+1)). 📍 moved down one, as promised ✨
• ISTARTM — ISTARTM is INTEGER. (that's all it says. no notes. mysterious main character energy 🕵️‍♀️)
• ISTOPM — ISTOPM is INTEGER. updates to (A,B) are restricted to (istartm:k+2,k:istopm). and it's assumed — without checking, bestie, no vibe check at all 😭 — that istartm <= k+1 and k+2 <= istopm.
• IHI — IHI is INTEGER. (again: that's it. she said very little and left 🌸)
• A — A is COMPLEX array, dimension (LDA,N). 💖
• LDA — LDA is INTEGER. the leading dimension of A as declared in the calling procedure.
• B — B is COMPLEX 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+3-qStart of Q. (note: written qStart in the original, lowercase s, we do not fix, we respect 💅)
• Q — Q is COMPLEX 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+2-qStart of Z. (again qStart, not zStart. we keep it exactly as the page says, no cap 🙈)
• Z — Z is COMPLEX array, dimension (LDZ,NZ). 🎀
• LDZ — LDZ is INTEGER. the leading dimension of Q as declared in the calling procedure. (yes it says Q here on the LDZ entry. that's what the page says. we're not editing the source, we're just reading it 💀)

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🧚 Author 🧚

Thijs Steel, KU Leuven 💜

🍓 Date 🍓

May 2020 📅

🔥 Definition 🔥

Definition at line 171 of file claqz1.f. 📌

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⭐ Author ⭐

Generated automatically by Doxygen for LAPACK from the source code. 🤖✨ (the robots wrote this one, we just gave it a glow-up)

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k bye bestie 🫶 this was LAPACK, Version 3.12.0, and the page is SRC/claqz1.f(3) — go chase that bulge, slay 💅🎀