dlatm7.f - Man Page

    DLATM7 computes the entries of D as specified by MODE
    COND and IRSIGN. IDIST and ISEED determine the generation
    of random numbers. DLATM7 is called by DLATMT 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   - DOUBLE PRECISION
           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 DLATM7
           to continue the same random number sequence.
           Changed on exit.

  D      - DOUBLE PRECISION 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