TESTING/MATGEN/slatm1.f(3)

NAME
TESTING/MATGEN/slatm1.f

SYNOPSIS

  Functions/Subroutines
subroutine slatm1 (mode, cond, irsign, idist, iseed, d, n, info)
SLATM1

Function/Subroutine Documentation

  subroutine slatm1 (integer mode, real cond, integer irsign, integer idist, integer, dimension( 4 ) iseed, real, dimension( * ) d, integer n, integer info)

SLATM1

Purpose:

        SLATM1 computes the entries of D(1..N) as specified by
        MODE, COND and IRSIGN. IDIST and ISEED determine the generation
        of random numbers. SLATM1 is called by SLATMR 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 REAL
               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 SLATM1
               to continue the same random number sequence.
               Changed on exit.

    D

              D is REAL 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 slatm1.f.

Author

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