SRC/cunm2l.f(3)

🌟 NAME 🌟

okay so bestie, this page is SRC/cunm2l.f(3) from the Library Functions Manual, and it is literally all about SRC/cunm2l.f. no cap.

---

✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

subroutine cunm2l (side, trans, m, n, k, a, lda, tau, c, ldc, work, info)

CUNM2L multiplies a general matrix by the unitary matrix from a QL factorization determined by cgeqlf (unblocked algorithm). it's giving linear algebra royalty 💅

---

💖 Function/Subroutine Documentation 💖

subroutine cunm2l (character side, character trans, integer m, integer n, integer k, complex, dimension( lda, * ) a, integer lda, complex, dimension( * ) tau, complex, dimension( ldc, * ) c, integer ldc, complex, dimension( * ) work, integer info)

CUNM2L multiplies a general matrix by the unitary matrix from a QL factorization determined by cgeqlf (unblocked algorithm). yes bestie, it's the same iconic subroutine, now with full signature energy ✨

🎀 Purpose 🎀

CUNM2L overwrites the general complex m-by-n matrix C with:

Q * C  if SIDE = 'L' and TRANS = 'N', or

Q**H* C  if SIDE = 'L' and TRANS = 'C', or

C * Q  if SIDE = 'R' and TRANS = 'N', or

C * Q**H if SIDE = 'R' and TRANS = 'C',

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 CGEQLF. 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': apply Q (No transpose)
• = 'C': apply Q**H (Conjugate transpose)

M

M is INTEGER

The number of rows of the matrix C. M >= 0. bestie, zero rows is allowed, the math said so 🫶

N

N is INTEGER

The number of columns of the matrix C. N >= 0. same vibe check: zero is valid ✨

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,K)

The i-th column must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by CGEQLF in the last k columns of its array argument A.

A is modified by the routine but restored on exit. so it's a little chaotic mid-routine, but it comes back home safe 💖

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 array, dimension (K)

TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CGEQLF.

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 Q**H*C or C*Q**H or C*Q. she gets a whole new look, no cap 👑

LDC

LDC is INTEGER

The leading dimension of the array C. LDC >= max(1,M).

WORK

WORK is COMPLEX array, dimension

(N) if SIDE = 'L',
(M) if SIDE = 'R'

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 157 of file cunm2l.f.

---

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

---

xoxo, LAPACK Version 3.12.0 💅 — source: SRC/cunm2l.f(3) 🫶