slagsy.f - Man Page

subroutine slagsy (n, k, d, a, lda, iseed, work, info)
SLAGSY

SLAGSY

Purpose:

 SLAGSY generates a real symmetric matrix A, by pre- and post-
 multiplying a real diagonal matrix D with a random orthogonal matrix:
 A = U*D*U'. The semi-bandwidth may then be reduced to k by additional
 orthogonal transformations.

Parameters

N

          N is INTEGER
          The order of the matrix A.  N >= 0.

K

          K is INTEGER
          The number of nonzero subdiagonals within the band of A.
          0 <= K <= N-1.

D

          D is REAL array, dimension (N)
          The diagonal elements of the diagonal matrix D.

A

          A is REAL array, dimension (LDA,N)
          The generated n by n symmetric matrix A (the full matrix is
          stored).

LDA

          LDA is INTEGER
          The leading dimension of the array A.  LDA >= N.

ISEED

          ISEED is INTEGER array, dimension (4)
          On entry, the seed of the random number generator; the array
          elements must be between 0 and 4095, and ISEED(4) must be
          odd.
          On exit, the seed is updated.

WORK

          WORK is REAL array, dimension (2*N)

INFO

          INFO is INTEGER
          = 0: successful exit
          < 0: if INFO = -i, the i-th argument had an illegal value

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 100 of file slagsy.f.