SLAQZ4(3)

🌟 SLAQZ4(3) 🌟

okay bestie, welcome to the Library Functions Manual entry for SLAQZ4(3) — and yes, the NAME line is literally a whole source path, because Fortran documentation said “main character energy” and committed to it 💅

🎀 NAME 🎀

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/slaqz4.f

That’s it. That’s the NAME. The path ate and left no crumbs ✨

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

subroutine SLAQZ4 (ilschur, ilq, ilz, n, ilo, ihi, nshifts,
           nblock_desired, sr, si, ss, a, lda, b, ldb, q, ldq, z, ldz, qc,
           ldqc, zc, ldzc, work, lwork, info)
           SLAQZ4

🦋 Function/Subroutine Documentation 🦋

The full signature is giving “I know every intent and every dimension, periodt”:

subroutine SLAQZ4 (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, real, dimension( * ), intent(inout) sr, real,
       dimension( * ), intent(inout) si, real, dimension( * ), intent(inout)
       ss, real, dimension( lda, * ), intent(inout) a, integer, intent(in) lda,
       real, dimension( ldb, * ), intent(inout) b, integer, intent(in) ldb,
       real, dimension( ldq, * ), intent(inout) q, integer, intent(in) ldq,
       real, dimension( ldz, * ), intent(inout) z, integer, intent(in) ldz,
       real, dimension( ldqc, * ), intent(inout) qc, integer, intent(in) ldqc,
       real, dimension( ldzc, * ), intent(inout) zc, integer, intent(in) ldzc,
       real, dimension( * ), intent(inout) work, integer, intent(in) lwork,
       integer, intent(out) info)
       SLAQZ4

🫶 Purpose 🫶

The raw purpose note is:

!>
!> SLAQZ4 Executes a single multishift QZ sweep
!>

So like — it executes a single multishift QZ sweep. That’s the whole vibe. Slay 💅

🌸 Parameters 🌸

• 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.
• SR — SR is REAL array. SR contains the real parts of the shifts to use.
• SI — SI is REAL array. SI contains the imaginary parts of the shifts to use.
• SS — SS is REAL array. SS contains the scale of the shifts to use.
• A — A is REAL array, dimension (LDA, N).
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max( 1, N ).
• B — B is REAL array, dimension (LDB, N).
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max( 1, N ).
• Q — Q is REAL array, dimension (LDQ, N).
• LDQ — LDQ is INTEGER.
• Z — Z is REAL array, dimension (LDZ, N).
• LDZ — LDZ is INTEGER.
• QC — QC is REAL array, dimension (LDQC, NBLOCK_DESIRED).
• LDQC — LDQC is INTEGER.
• ZC — ZC is REAL array, dimension (LDZC, NBLOCK_DESIRED).
• LDZC — the raw page literally says LDZ is INTEGER here. yes, bestie, LDZ, not LDZC — I’m not fixing it, that’s what it says 💀
• WORK — WORK is REAL 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

⭐ Date ⭐

May 2020

Definition at line 210 of file slaqz4.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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