dlatm1.f - Man Page

subroutine dlatm1 (mode, cond, irsign, idist, iseed, d, n, info)
DLATM1

DLATM1

Purpose:

    DLATM1 computes the entries of D(1..N) as specified by
    MODE, COND and IRSIGN. IDIST and ISEED determine the generation
    of random numbers. DLATM1 is called by DLATMR to generate
    random test matrices for LAPACK programs.

Parameters

MODE

          MODE is 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:N)=1.0/COND
           MODE = 2 sets D(1:N-1)=1 and D(N)=1.0/COND
           MODE = 3 sets D(I)=COND**(-(I-1)/(N-1))
           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

          COND is DOUBLE PRECISION
           On entry, used as described under MODE above.
           If used, it must be >= 1. Not modified.

IRSIGN

          IRSIGN is 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

          IDIST is INTEGER
           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

          ISEED is 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 DLATM1
           to continue the same random number sequence.
           Changed on exit.

D

          D is DOUBLE PRECISION array, dimension ( N )
           Array to be computed according to MODE, COND and IRSIGN.
           May be changed on exit if MODE is nonzero.

N

          N is INTEGER
           Number of entries of D. Not modified.

INFO

          INFO is 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 134 of file dlatm1.f.