SRC/cunm22.f(3)

📦
version 3.12.1 · 7 versions
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💖 NAME 💖

okay so this is the SRC/cunm22.f page from the Library Functions Manual, and the whole page is literally about SRC/cunm22.f 💅

🎀 SYNOPSIS 🎀

🧚 Functions/Subroutines 🧚

  • subroutine cunm22 — CUNM22 multiplies a general matrix by a banded unitary matrix.
subroutine cunm22 (side, trans, m, n, n1, n2, q, ldq, c, ldc, work,
    lwork, info)

CUNM22 multiplies a general matrix by a banded unitary matrix.

💅 Function/Subroutine Documentation 💅

subroutine cunm22 (character side, character trans, integer m, integer n,
    integer n1, integer n2, complex, dimension( ldq, * ) q, integer ldq,
    complex, dimension( ldc, * ) c, integer ldc, complex, dimension( * )
    work, integer lwork, integer info)

CUNM22 multiplies a general matrix by a banded unitary matrix.

✨ Purpose ✨

bestie, here’s the whole vibe: CUNM22 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 of order NQ, with NQ = M if SIDE = 'L' and NQ = N if SIDE = 'R'.

The unitary matrix Q processes a 2-by-2 block structure

        [  Q11  Q12  ]
    Q = [            ]
        [  Q21  Q22  ],

where Q12 is an N1-by-N1 lower triangular matrix and Q21 is an N2-by-N2 upper triangular matrix.

🫶 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.

N

N is INTEGER.

The number of columns of the matrix C. N >= 0.

N1, N2

N1 is INTEGER.

N2 is INTEGER.

The dimension of Q12 and Q21, respectively. N1, N2 >= 0.

The following requirement must be satisfied: N1 + N2 = M if SIDE = 'L' and N1 + N2 = N if SIDE = 'R'.

Q

Q is COMPLEX array, dimension (LDQ,M) if SIDE = 'L', and (LDQ,N) if SIDE = 'R'.

LDQ

LDQ is INTEGER.

The leading dimension of the array Q.

LDQ >= max(1,M) if SIDE = 'L'; LDQ >= max(1,N) if SIDE = 'R'.

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.

LDC

LDC is INTEGER.

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

WORK

WORK is COMPLEX 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 optimum performance LWORK >= M*N.

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 160 of file cunm22.f.

📜 Author 📜

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okay bye bestie, this iconic little page is from LAPACK Version 3.12.0, and the file is SRC/cunm22.f(3) 💖✨🦋

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