SRC/slaqz3.f(3)

💖 SRC/slaqz3.f(3) 💖

okay bestie, this page is from the Library Functions Manual, and it's all about SRC/slaqz3.f. That's the whole NAME vibe, no cap: SRC/slaqz3.f.

✨ SYNOPSIS ✨

🦋 Functions/Subroutines 🦋

recursive subroutine slaqz3 (ilschur, ilq, ilz, n, ilo, ihi, nw, a, lda,
    b, ldb, q, ldq, z, ldz, ns, nd, alphar, alphai, beta, qc, ldqc, zc,
    ldzc, work, lwork, rec, info)
SLAQZ3

💅 Function/Subroutine Documentation 💅

recursive subroutine slaqz3 (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, 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, integer,
    intent(out) ns, integer, intent(out) nd, real, dimension( * ),
    intent(inout) alphar, real, dimension( * ), intent(inout) alphai, real,
    dimension( * ), intent(inout) beta, real, dimension( ldqc, * ) qc,
    integer, intent(in) ldqc, real, dimension( ldzc, * ) zc, integer,
    intent(in) ldzc, real, dimension( * ) work, integer, intent(in) lwork,
    integer, intent(in) rec, integer, intent(out) info)
SLAQZ3

✨ Purpose ✨

SLAQZ3 performs AED. That's the whole purpose, bestie — short and iconic.

🌸 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. ILO and IHI mark the rows and columns of (A,B) which are to be normalized.
• NW — NW is INTEGER. The desired size of the deflation window.
• 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.
• NS — NS is INTEGER. The number of unconverged eigenvalues available to use as shifts.
• ND — ND is INTEGER. The number of converged eigenvalues found.
• ALPHAR — ALPHAR is REAL array, dimension (N). The real parts of each scalar alpha defining an eigenvalue of GNEP.
• ALPHAI — ALPHAI is REAL array, dimension (N). The imaginary parts of each scalar alpha defining an eigenvalue of GNEP. If ALPHAI(j) is zero, then the j-th eigenvalue is real; if positive, then the j-th and (j+1)-st eigenvalues are a complex conjugate pair, with ALPHAI(j+1) = -ALPHAI(j).
• BETA — BETA is REAL array, dimension (N). The scalars beta that define the eigenvalues of GNEP. Together, the quantities alpha = (ALPHAR(j),ALPHAI(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 — QC is REAL array, dimension (LDQC, NW).
• LDQC — LDQC is INTEGER.
• ZC — ZC is REAL array, dimension (LDZC, NW).
• LDZC — the description literally reads LDZ is INTEGER here — yes, LDZ, not LDZC — and I'm keeping the source exactly as-is, bestie.
• 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.
• REC — REC is INTEGER. REC indicates the current recursion level. Should be set to 0 on first call.
• 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 ⭐

Definition at line 234 of file slaqz3.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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💖 cute little footer sign-off, because we're done: LAPACK, Version 3.12.0, page SRC/slaqz3.f(3), date May 2020 — slay, bye bestie! 💖