TESTING/MATGEN/slaror.f(3)

NAME
TESTING/MATGEN/slaror.f

SYNOPSIS

  Functions/Subroutines
subroutine slaror (side, init, m, n, a, lda, iseed, x, info)
SLAROR

Function/Subroutine Documentation

  subroutine slaror (character side, character init, integer m, integer n, real, dimension( lda, * ) a, integer lda, integer, dimension( 4 ) iseed, real, dimension( * ) x, integer info)

SLAROR

Purpose:

    !>
    !> SLAROR pre- or post-multiplies an M by N matrix A by a random
    !> orthogonal matrix U, overwriting A.  A may optionally be initialized
    !> to the identity matrix before multiplying by U.  U is generated using
    !> the method of G.W. Stewart (SIAM J. Numer. Anal. 17, 1980, 403-409).
    !>

Parameters
    SIDE

    !>          SIDE is CHARACTER*1
    !>          Specifies whether A is multiplied on the left or right by U.
    !>          = 'L':         Multiply A on the left (premultiply) by U
    !>          = 'R':         Multiply A on the right (postmultiply) by U'
    !>          = 'C' or 'T':  Multiply A on the left by U and the right
    !>                          by U' (Here, U' means U-transpose.)
    !>

    INIT

    !>          INIT is CHARACTER*1
    !>          Specifies whether or not A should be initialized to the
    !>          identity matrix.
    !>          = 'I':  Initialize A to (a section of) the identity matrix
    !>                   before applying U.
    !>          = 'N':  No initialization.  Apply U to the input matrix A.
    !>
    !>          INIT = 'I' may be used to generate square or rectangular
    !>          orthogonal matrices:
    !>
    !>          For M = N and SIDE = 'L' or 'R', the rows will be orthogonal
    !>          to each other, as will the columns.
    !>
    !>          If M < N, SIDE = 'R' produces a dense matrix whose rows are
    !>          orthogonal and whose columns are not, while SIDE = 'L'
    !>          produces a matrix whose rows are orthogonal, and whose first
    !>          M columns are orthogonal, and whose remaining columns are
    !>          zero.
    !>
    !>          If M > N, SIDE = 'L' produces a dense matrix whose columns
    !>          are orthogonal and whose rows are not, while SIDE = 'R'
    !>          produces a matrix whose columns are orthogonal, and whose
    !>          first M rows are orthogonal, and whose remaining rows are
    !>          zero.
    !>

    M

    !>          M is INTEGER
    !>          The number of rows of A.
    !>

    N

    !>          N is INTEGER
    !>          The number of columns of A.
    !>

    A

    !>          A is REAL array, dimension (LDA, N)
    !>          On entry, the array A.
    !>          On exit, overwritten by U A ( if SIDE = 'L' ),
    !>           or by A U ( if SIDE = 'R' ),
    !>           or by U A U' ( if SIDE = 'C' or 'T').
    !>

    LDA

    !>          LDA is INTEGER
    !>          The leading dimension of the array A.  LDA >= max(1,M).
    !>

    ISEED

    !>          ISEED is INTEGER array, dimension (4)
    !>          On entry ISEED specifies the seed of the random number
    !>          generator. The array elements should be between 0 and 4095;
    !>          if not they will be reduced mod 4096.  Also, ISEED(4) must
    !>          be odd.  The random number generator uses a linear
    !>          congruential sequence limited to small integers, and so
    !>          should produce machine independent random numbers. The
    !>          values of ISEED are changed on exit, and can be used in the
    !>          next call to SLAROR to continue the same random number
    !>          sequence.
    !>

    X

    !>          X is REAL array, dimension (3*MAX( M, N ))
    !>          Workspace of length
    !>              2*M + N if SIDE = 'L',
    !>              2*N + M if SIDE = 'R',
    !>              3*N     if SIDE = 'C' or 'T'.
    !>

    INFO

    !>          INFO is INTEGER
    !>          An error flag.  It is set to:
    !>          = 0:  normal return
    !>          < 0:  if INFO = -k, the k-th argument had an illegal value
    !>          = 1:  if the random numbers generated by SLARND are bad.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 145 of file slaror.f.

Author

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