TESTING/MATGEN/dlaror.f(3)

NAME
TESTING/MATGEN/dlaror.f

SYNOPSIS

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

Function/Subroutine Documentation

  subroutine dlaror (character side, character init, integer m, integer n, double precision, dimension( lda, * ) a, integer lda, integer, dimension( 4 ) iseed, double precision, dimension( * ) x, integer info)

DLAROR

Purpose:

     DLAROR 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 DOUBLE PRECISION 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 DLAROR to continue the same random number
              sequence.

    X

              X is DOUBLE PRECISION 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 DLARND are bad.

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 145 of file dlaror.f.

Author

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