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sgemqrt.f(3) LAPACK sgemqrt.f(3)

NAME

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

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