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## zunm2r()

subroutine zunm2r | ( | 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 | info )

ZUNM2R multiplies a general matrix by the unitary matrix from a QR factorization determined by cgeqrf (unblocked algorithm).

Download ZUNM2R + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> ZUNM2R 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(1) H(2) . . . H(k)
      !>
      !> as returned by ZGEQRF. Q is of order m if SIDE = 'L' and of order n
      !> if SIDE = 'R'.
      !>

Parameters

  [in]

  SIDE

      !>          SIDE is CHARACTER*1
      !>          = 'L': apply Q or Q**H from the Left
      !>          = 'R': apply Q or Q**H from the Right
      !>

  [in]

  TRANS

      !>          TRANS is CHARACTER*1
      !>          = 'N': apply Q  (No transpose)
      !>          = 'C': apply Q**H (Conjugate transpose)
      !>

  [in]

  M

      !>          M is INTEGER
      !>          The number of rows of the matrix C. M >= 0.
      !>

  [in]

  N

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

  [in]

  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.
      !>

  [in]

  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
      !>          ZGEQRF in the first k columns of its array argument A.
      !>          A is modified by the routine but restored on exit.
      !>

  [in]

  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).
      !>

  [in]

  TAU

      !>          TAU is COMPLEX*16 array, dimension (K)
      !>          TAU(i) must contain the scalar factor of the elementary
      !>          reflector H(i), as returned by ZGEQRF.
      !>

  [in,out]

  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.
      !>

  [in]

  LDC

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

  [out]

  WORK

      !>          WORK is COMPLEX*16 array, dimension
      !>                                   (N) if SIDE = 'L',
      !>                                   (M) if SIDE = 'R'
      !>

  [out]

  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.