DLATM1
Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
June 2010
June 2010
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 SLATMR to generate
random test matrices for LAPACK programs.
MODE, COND and IRSIGN. IDIST and ISEED determine the generation
of random numbers. DLATM1 is called by SLATMR to generate
random test matrices for LAPACK programs.
Arguments
| MODE |
(input) 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 |
(input) DOUBLE PRECISION
On entry, used as described under MODE above.
If used, it must be >= 1. Not modified. |
| IRSIGN |
(input) 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 |
(input) 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 |
(input/output) 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 |
(input/output) 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 |
(input) INTEGER
Number of entries of D. Not modified.
|
| INFO |
(output) 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 |