SRC/zunmql.f(3)

💅 SRC/zunmql.f 💅

okay bestie, this is the Library Functions Manual page for SRC/zunmql.f — the ZUNMQL routine — and we're gonna make it make sense. ✨

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🌸 NAME 🌸

SRC/zunmql.f

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

subroutine zunmql (side, trans, m, n, k, a, lda, tau, c, ldc, work,
    lwork, info)
    ZUNMQL

💖 Function/Subroutine Documentation 💖

🦋 subroutine zunmql 🦋

subroutine zunmql (character side, character trans, integer m, integer n,
    integer k, complex*16, dimension( lda, * ) a, integer lda, complex*16,
    dimension( * ) tau, complex*16, dimension( ldc, * ) c, integer ldc,
    complex*16, dimension( * ) work, integer lwork, integer info)

ZUNMQL 💅

🎯 Purpose 🎯

okay so here's the literal tea, no cap:

!>
!> ZUNMQL overwrites the general complex M-by-N matrix C with
!>
!>                 SIDE = 'L'     SIDE = 'R'
!> TRANS = 'N':      Q * C          C * Q
!> TRANS = 'C':      Q**H * C       C * Q**H
!>
!> where Q is a complex unitary matrix defined as the product of k
!> elementary reflectors
!>
!>       Q = H(k) . . . H(2) H(1)
!>
!> as returned by ZGEQLF. Q is of order M if SIDE = 'L' and of order N
!> if SIDE = 'R'.
!>

so yeah, C gets overwritten — it's giving main character energy, not a read-only lil bystander. 💅

🌸 Parameters 🌸

now the parameters, one by one, because we do not skip details in this group chat:

• SIDE — SIDE is CHARACTER*1; = 'L': apply Q or QH from the Left; = 'R': apply Q or QH from the Right.
• TRANS — TRANS is CHARACTER*1; = 'N': No transpose, apply Q; = 'C': Conjugate transpose, apply Q**H.
• M — M is INTEGER; the number of rows of the matrix C. M >= 0.
• N — N is INTEGER; the number of columns of the matrix C. N >= 0.
• K — K is INTEGER; the number of elementary reflectors whose product defines the matrix Q. If SIDE = 'L', M >= K >= 0; if SIDE = 'R', N >= K >= 0.
• A — A is COMPLEX*16 array, dimension (LDA,K). The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by ZGEQLF in the last k columns of its array argument A.
• LDA — LDA is INTEGER; the leading dimension of the array A. If SIDE = 'L', LDA >= max(1,M); if SIDE = 'R', LDA >= max(1,N).
• TAU — TAU is COMPLEX*16 array, dimension (K). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by ZGEQLF.
• C — C is COMPLEX*16 array, dimension (LDC,N). On entry, the M-by-N matrix C. On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.
• LDC — LDC is INTEGER; the leading dimension of the array C. LDC >= max(1,M).
• WORK — WORK is COMPLEX*16 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. If SIDE = 'L', LWORK >= max(1,N); if SIDE = 'R', LWORK >= max(1,M). For good performance, LWORK should generally be larger. 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 👑

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

Definition at line 165 of file zunmql.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

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k bye bestie 💅 the footer vibes are LAPACK Version 3.12.0 and SRC/zunmql.f(3) — mwah 🫶✨