SRC/cgemlq.f(3)

🎀 SRC/cgemlq.f 🎀

okay so this is the Library Functions Manual page for SRC/cgemlq.f, and bestie, it's giving serious LAPACK subroutine energy. no cap. 💅

🌸 NAME 🌸

SRC/cgemlq.f

🦋 SYNOPSIS 🦋

✨ Functions/Subroutines ✨

• subroutine cgemlq — CGEMLQ

       subroutine cgemlq (side, trans, m, n, k, a, lda, t, tsize, c, ldc, work,
           lwork, info)

CGEMLQ

💖 Function/Subroutine Documentation 💖

🧚 subroutine cgemlq — CGEMLQ 🧚

   subroutine cgemlq (character side, character trans, integer m, integer n,
       integer k, complex, dimension( lda, * ) a, integer lda, complex,
       dimension( * ) t, integer tsize, complex, dimension( ldc, * ) c, integer
       ldc, complex, dimension( * ) work, integer lwork, integer info)
       CGEMLQ

💫 Purpose 💫

the way this one is literally here to overwrite the general real M-by-N matrix C. here's the exact vibe:

!>
!>     CGEMLQ overwrites the general real 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 blocked elementary reflectors computed by short wide
!>      LQ factorization (CGELQ)
!>
!>

🍓 Parameters 🍓

• SIDE — SIDE is CHARACTER*1
  • = 'L': apply Q or Q**H from the Left;
  • = 'R': apply Q or Q**H 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 A. 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 array, dimension (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R' Part of the data structure to represent Q as returned by CGELQ.
• LDA — LDA is INTEGER The leading dimension of the array A. LDA >= max(1,K).
• T — T is COMPLEX array, dimension (MAX(5,TSIZE)). Part of the data structure to represent Q as returned by CGELQ.
• TSIZE — TSIZE is INTEGER The dimension of the array T. TSIZE >= 5.
• C — C is COMPLEX array, dimension (LDC,N) On entry, the M-by-N matrix C. On exit, C is overwritten by Q*C or QH*C or C*QH or C*Q.
• LDC — LDC is INTEGER The leading dimension of the array C. LDC >= max(1,M).
• WORK — (workspace) COMPLEX array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the minimal LWORK.
• LWORK — LWORK is INTEGER The dimension of the array WORK. LWORK >= 1. If LWORK = -1, then a workspace query is assumed. The routine only calculates the size of the WORK array, returns this value as WORK(1), and no error message related to WORK 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.

🔥 Further Details 🔥

These details are particular for this LAPACK implementation. Users should not take them for granted. These details may change in the future, and are not likely true for another LAPACK implementation. These details are relevant if one wants to try to understand the code. They are not part of the interface.

In this version,

• T(2): row block size (MB)
• T(3): column block size (NB)
• T(6:TSIZE): data structure needed for Q, computed by CLASWQR or CGELQT

Depending on the matrix dimensions M and N, and row and column block sizes MB and NB returned by ILAENV, CGELQ will use either CLASWLQ (if the matrix is wide-and-short) or CGELQT to compute the LQ factorization.

This version of CGEMLQ will use either CLAMSWLQ or CGEMLQT to multiply matrix Q by another matrix.

Further Details in CLAMSWLQ or CGEMLQT.

📌 Definition at line 171 of file cgemlq.f. 📌

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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