SRC/zunmlq.f(3)

💅 SRC/zunmlq.f 💅

okay so this page came straight from the Library Functions Manual, and it’s giving “complex linear algebra bestie” energy. We’re talking ZUNMLQ, no cap. It’s a subroutine, it lives in SRC/zunmlq.f, and it is lowkey iconic in a very nerdy way. 🫶

🌸 NAME 🌸

SRC/zunmlq.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines

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

📚 Function/Subroutine Documentation 📚

Here’s the whole signature, bestie — typed exactly how the Fortran girlies wrote it:

   subroutine zunmlq (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)
       ZUNMLQ

💖 Purpose 💖

okay so ZUNMLQ 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 . . . H(2)**H H(1)**H

as returned by ZGELQF. Q is of order M if SIDE = 'L' and of order N if SIDE = 'R'. periodt. 💅

🧩 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 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,M) if SIDE = 'L', (LDA,N) if SIDE = 'R'. The i-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by ZGELQF in the first k rows of its array argument A.
• LDA — LDA is INTEGER; the leading dimension of the array A. LDA >= max(1,K).
• TAU — TAU is COMPLEX*16 array, dimension (K); TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by ZGELQF.
• 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 zunmlq.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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okay that’s the whole page bestie! massive love to LAPACK Version 3.12.0 and this page is SRC/zunmlq.f(3) — bye 💅✨