sgemlqt.f(3)

NAME
sgemlqt.f

SYNOPSIS

  Functions/Subroutines
subroutine sgemlqt (SIDE, TRANS, M, N, K, MB, V, LDV, T, LDT, C, LDC, WORK, INFO)

Function/Subroutine Documentation

  subroutine sgemlqt (character SIDE, character TRANS, integer M, integer N, integer K, integer MB, real, dimension( ldv, * ) V, integer LDV, real, dimension( ldt, * ) T, integer LDT, real, dimension( ldc, * ) C, integer LDC, real, dimension( * ) WORK, integer INFO)

Purpose:

DGEMLQT 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 DGELQT.

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;
              = 'C':  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.

    MB

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

    V

              V is REAL array, dimension
                                   (LDV,M) if SIDE = 'L',
                                   (LDV,N) if SIDE = 'R'
              The i-th row must contain the vector which defines the
              elementary reflector H(i), for i = 1,2,...,k, as returned by
              DGELQT in the first K rows of its array argument A.

    LDV

              LDV is INTEGER
              The leading dimension of the array V. LDV >= max(1,K).

    T

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

    LDT

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

    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*MB if SIDE = 'L', or  M*MB 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 2017

Definition at line 153 of file sgemlqt.f.

Author

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