SRC/zunm2r.f(3) Library Functions Manual SRC/zunm2r.f(3)

SRC/zunm2r.f


subroutine zunm2r (side, trans, m, n, k, a, lda, tau, c, ldc, work, info)
ZUNM2R multiplies a general matrix by the unitary matrix from a QR factorization determined by cgeqrf (unblocked algorithm).

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

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

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.

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,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.

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

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
                                   (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 zunm2r.f.

Generated automatically by Doxygen for LAPACK from the source code.

Version 3.12.0 LAPACK