sgemqrt.f man page

sgemqrt.f —

Synopsis

Functions/Subroutines

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

Function/Subroutine Documentation

subroutine sgemqrt (characterSIDE, characterTRANS, integerM, integerN, integerK, integerNB, real, dimension( ldv, * )V, integerLDV, real, dimension( ldt, * )T, integerLDT, real, dimension( ldc, * )C, integerLDC, real, dimension( * )WORK, integerINFO)

SGEMQRT  

Purpose:

 SGEMQRT overwrites the general real M-by-N matrix C with

                 SIDE = 'L'     SIDE = 'R'
 TRANS = 'N':      Q C            C Q
 TRANS = 'T':   Q**T C            C Q**T

 where Q is a real orthogonal matrix defined as the product of K
 elementary reflectors:

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

 generated using the compact WY representation as returned by SGEQRT. 

 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**T from the Left;
          = 'R': apply Q or Q**T from the Right.

TRANS

          TRANS is CHARACTER*1
          = 'N':  No transpose, apply Q;
          = 'T':  Transpose, apply Q**T.

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.

NB

          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

          V is REAL 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

          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

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

LDT

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

C

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

LDC

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

WORK

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

Date:

November 2013

Definition at line 168 of file sgemqrt.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

sgemqrt(3) is an alias of sgemqrt.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK