ZGBBRD(3)

🌸 NAME 🌸

Okay bestie, this is the page for ZGBBRD(3) — aka the zgbbrd.f(3) page from the Library Functions Manual. The source file path is exactly this:

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

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✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

The function/subroutine signature is:

subroutine ZGBBRD (vect, m, n, ncc, kl, ku, ab, ldab, d, e, q, ldq, pt,
    ldpt, c, ldc, work, rwork, info)
    ZGBBRD

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🦋 Function/Subroutine Documentation 🦋

Here's the fully typed signature, bestie — every argument in its natural habitat:

subroutine ZGBBRD (character vect, integer m, integer n, integer ncc,
    integer kl, integer ku, complex*16, dimension( ldab, * ) ab, integer
    ldab, double precision, dimension( * ) d, double precision, dimension( *
    ) e, complex*16, dimension( ldq, * ) q, integer ldq, complex*16,
    dimension( ldpt, * ) pt, integer ldpt, complex*16, dimension( ldc, * )
    c, integer ldc, complex*16, dimension( * ) work, double precision,
    dimension( * ) rwork, integer info)
    ZGBBRD

It's giving main character routine, fr fr.

💖 Purpose 💖

So the whole vibe: ZGBBRD reduces a complex general m-by-n band matrix A to real upper bidiagonal form B by a unitary transformation:

Q**H * A * P = B

It computes B, and optionally forms Q or P**H, or computes Q**H*C for a given matrix C. Slay. 💅

🧸 Parameters 🧸

• VECT — CHARACTER*1. This is the little switch that says whether Q and P**H are gonna be formed or not. The choices are:
  • = 'N': do not form Q or P**H;
  • = 'Q': form Q only;
  • = 'P': form P**H only;
  • = 'B': form both.
• M — INTEGER. The number of rows of the matrix A. M >= 0.
• N — INTEGER. The number of columns of the matrix A. N >= 0.
• NCC — INTEGER. The number of columns of the matrix C. NCC >= 0.
• KL — INTEGER. The number of subdiagonals of the matrix A. KL >= 0.
• KU — INTEGER. The number of superdiagonals of the matrix A. KU >= 0.
• AB — COMPLEX*16 array, dimension (LDAB,N). On entry, this is the m-by-n band matrix A, stored in rows 1 to KL+KU+1. The j-th column of A is stored in the j-th column of the array AB like this:
  • AB(ku+1+i-j,j) = A(i,j) for max(1,j-ku)<=i<=min(m,j+kl). On exit, A is overwritten by values generated during the reduction. 🫶
• LDAB — INTEGER. The leading dimension of the array A. LDAB >= KL+KU+1.
• D — DOUBLE PRECISION array, dimension (min(M,N)). The diagonal elements of the bidiagonal matrix B.
• E — DOUBLE PRECISION array, dimension (min(M,N)-1). The superdiagonal elements of the bidiagonal matrix B.
• Q — COMPLEX*16 array, dimension (LDQ,M).
  • If VECT = 'Q' or 'B', this is the m-by-m unitary matrix Q.
  • If VECT = 'N' or 'P', the array Q is not referenced.
• LDQ — INTEGER. The leading dimension of the array Q.
  • LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise.
• PT — COMPLEX*16 array, dimension (LDPT,N).
  • If VECT = 'P' or 'B', this is the n-by-n unitary matrix P'.
  • If VECT = 'N' or 'Q', the array PT is not referenced.
• LDPT — INTEGER. The leading dimension of the array PT.
  • LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise.
• C — COMPLEX*16 array, dimension (LDC,NCC).
  • On entry, an m-by-ncc matrix C.
  • On exit, C is overwritten by Q**H*C.
  • C is not referenced if NCC = 0.
• LDC — INTEGER. The leading dimension of the array C.
  • LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0.
• WORK — COMPLEX*16 array, dimension (max(M,N)).
• RWORK — DOUBLE PRECISION array, dimension (max(M,N)).
• INFO — INTEGER.
  • = 0: successful exit.
  • < 0: if INFO = -i, the i-th argument had an illegal value.

👑 Author 👑

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

Definition at line 191 of file zgbbrd.f. Periodt. 💜

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💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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That's the whole page, bestie! 🫶 Footer/source-version tea: LAPACK, Version 3.12.0, and the path shows up as /home/abui...RC/zgbbrd.f(3) — no separate date popped up in this copy, just that footer line doing its thing. 💖✨