zgemqrt.f man page

zgemqrt.f —



subroutine zgemqrt (SIDE, TRANS, M, N, K, NB, V, LDV, T, LDT, C, LDC, WORK, INFO)

Function/Subroutine Documentation

subroutine zgemqrt (character SIDE, character TRANS, integer M, integer N, integer K, integer NB, complex*16, dimension( ldv, * ) V, integer LDV, complex*16, dimension( ldt, * ) T, integer LDT, complex*16, dimension( ldc, * ) C, integer LDC, complex*16, dimension( * ) WORK, integer INFO)



 ZGEMQRT 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 orthogonal matrix defined as the product of K
 elementary reflectors:

       Q = H(1) H(2) . . . H(K) = I - V T V**H

 generated using the compact WY representation as returned by ZGEQRT.

 Q is of order M if SIDE = 'L' and of order N  if SIDE = 'R'.


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


          TRANS is CHARACTER*1
          = 'N':  No transpose, apply Q;
          = 'C':  Transpose, apply Q**H.


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


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


          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.


          NB is INTEGER
          The block size used for the storage of T.  K >= NB >= 1.
          This must be the same value of NB used to generate T
          in CGEQRT.


          V is COMPLEX*16 array, dimension (LDV,K)
          The i-th column must contain the vector which defines the
          elementary reflector H(i), for i = 1,2,...,k, as returned by
          CGEQRT in the first K columns of its array argument A.


          LDV is INTEGER
          The leading dimension of the array V.
          If SIDE = 'L', LDA >= max(1,M);
          if SIDE = 'R', LDA >= max(1,N).


          T is COMPLEX*16 array, dimension (LDT,K)
          The upper triangular factors of the block reflectors
          as returned by CGEQRT, stored as a NB-by-N matrix.


          LDT is INTEGER
          The leading dimension of the array T.  LDT >= NB.


          C is COMPLEX*16 array, dimension (LDC,N)
          On entry, the M-by-N matrix C.
          On exit, C is overwritten by Q C, Q**H C, C Q**H or C Q.


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


          WORK is COMPLEX*16 array. The dimension of WORK is
           N*NB if SIDE = 'L', or  M*NB if SIDE = 'R'.


          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.


December 2016

Definition at line 170 of file zgemqrt.f.


Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

The man page zgemqrt(3) is an alias of zgemqrt.f(3).

Sat Jun 24 2017 Version 3.7.1 LAPACK