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.

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

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.