SRC/zgbbrd.f(3)

💖 SRC/zgbbrd.f(3) 💖

okay bestie, welcome to the Library Functions Manual page for SRC/zgbbrd.f — yes, it's giving old-school Unix manual but make it cute ✨

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🌈 NAME 🌈

SRC/zgbbrd.f

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✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

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 🦋

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

🎀 Purpose 🎀

okay so 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. iconic behavior, no cap 💅

The routine computes B, and optionally forms Q or P**H, or computes Q**H*C for a given matrix C. that's the whole vibe 🫶

🌸 Parameters 🌸

• VECT — bestie, VECT is CHARACTER*1. It specifies whether or not the matrices Q and P**H are to be formed:
  • = 'N': do not form Q or P**H;
  • = 'Q': form Q only;
  • = 'P': form P**H only;
  • = 'B': form both.
• M — M is INTEGER. The number of rows of the matrix A. M >= 0.
• N — N is INTEGER. The number of columns of the matrix A. N >= 0.
• NCC — NCC is INTEGER. The number of columns of the matrix C. NCC >= 0.
• KL — KL is INTEGER. The number of subdiagonals of the matrix A. KL >= 0.
• KU — KU is INTEGER. The number of superdiagonals of the matrix A. KU >= 0.
• AB — AB is COMPLEX*16 array, dimension (LDAB,N). On entry, 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 as follows: 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 — LDAB is INTEGER. The leading dimension of the array A. LDAB >= KL+KU+1.
• D — D is DOUBLE PRECISION array, dimension (min(M,N)). The diagonal elements of the bidiagonal matrix B. 💖
• E — E is DOUBLE PRECISION array, dimension (min(M,N)-1). The superdiagonal elements of the bidiagonal matrix B.
• Q — Q is COMPLEX*16 array, dimension (LDQ,M). If VECT = 'Q' or 'B', the m-by-m unitary matrix Q. If VECT = 'N' or 'P', the array Q is not referenced.
• LDQ — LDQ is INTEGER. The leading dimension of the array Q. LDQ >= max(1,M) if VECT = 'Q' or 'B'; LDQ >= 1 otherwise.
• PT — PT is COMPLEX*16 array, dimension (LDPT,N). If VECT = 'P' or 'B', the n-by-n unitary matrix P'. If VECT = 'N' or 'Q', the array PT is not referenced.
• LDPT — LDPT is INTEGER. The leading dimension of the array PT. LDPT >= max(1,N) if VECT = 'P' or 'B'; LDPT >= 1 otherwise.
• C — C is 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 — LDC is INTEGER. The leading dimension of the array C. LDC >= max(1,M) if NCC > 0; LDC >= 1 if NCC = 0.
• WORK — WORK is COMPLEX*16 array, dimension (max(M,N)).
• RWORK — RWORK is DOUBLE PRECISION array, dimension (max(M,N)).
• INFO — INFO is 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.

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💜 Author 💜

Generated automatically by Doxygen for LAPACK from the source code.

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later bestie! this page is from LAPACK Version 3.12.0 and the source file SRC/zgbbrd.f(3) — the footer has no date, so no invented date, periodt 💅✨