TESTING/MATGEN/slatm7.f(3)

NAME
TESTING/MATGEN/slatm7.f

SYNOPSIS

  Functions/Subroutines
subroutine slatm7 (mode, cond, irsign, idist, iseed, d, n, rank, info)
SLATM7

Function/Subroutine Documentation

  subroutine slatm7 (integer mode, real cond, integer irsign, integer idist, integer, dimension( 4 ) iseed, real, dimension( * ) d, integer n, integer rank, integer info)

SLATM7

Purpose:

        SLATM7 computes the entries of D as specified by MODE
        COND and IRSIGN. IDIST and ISEED determine the generation
        of random numbers. SLATM7 is called by SLATMT to generate
        random test matrices.

      MODE   - INTEGER
               On entry describes how D is to be computed:
               MODE = 0 means do not change D.
               MODE = 1 sets D(1)=1 and D(2:RANK)=1.0/COND
               MODE = 2 sets D(1:RANK-1)=1 and D(RANK)=1.0/COND
               MODE = 3 sets D(I)=COND**(-(I-1)/(RANK-1)) I=1:RANK
               MODE = 4 sets D(i)=1 - (i-1)/(N-1)*(1 - 1/COND)
               MODE = 5 sets D to random numbers in the range
                        ( 1/COND , 1 ) such that their logarithms
                        are uniformly distributed.
               MODE = 6 set D to random numbers from same distribution
                        as the rest of the matrix.
               MODE < 0 has the same meaning as ABS(MODE), except that
                  the order of the elements of D is reversed.
               Thus if MODE is positive, D has entries ranging from
                  1 to 1/COND, if negative, from 1/COND to 1,
               Not modified.
      COND   - REAL
               On entry, used as described under MODE above.
               If used, it must be >= 1. Not modified.
      IRSIGN - INTEGER
               On entry, if MODE neither -6, 0 nor 6, determines sign of
               entries of D
               0 => leave entries of D unchanged
               1 => multiply each entry of D by 1 or -1 with probability .5
      IDIST  - CHARACTER*1
               On entry, IDIST specifies the type of distribution to be
               used to generate a random matrix .
               1 => UNIFORM( 0, 1 )
               2 => UNIFORM( -1, 1 )
               3 => NORMAL( 0, 1 )
               Not modified.
      ISEED  - INTEGER array, dimension ( 4 )
               On entry ISEED specifies the seed of the random number
               generator. 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 SLATM7
               to continue the same random number sequence.
               Changed on exit.
      D      - REAL array, dimension ( MIN( M , N ) )
               Array to be computed according to MODE, COND and IRSIGN.
               May be changed on exit if MODE is nonzero.
      N      - INTEGER
               Number of entries of D. Not modified.
      RANK   - INTEGER
               The rank of matrix to be generated for modes 1,2,3 only.
               D( RANK+1:N ) = 0.
               Not modified.
      INFO   - INTEGER
                0  => normal termination
               -1  => if MODE not in range -6 to 6
               -2  => if MODE neither -6, 0 nor 6, and
                      IRSIGN neither 0 nor 1
               -3  => if MODE neither -6, 0 nor 6 and COND less than 1
               -4  => if MODE equals 6 or -6 and IDIST not in range 1 to 3
               -7  => if N negative

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 120 of file slatm7.f.

Author

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