TESTING/MATGEN/dlagsy.f(3) | Library Functions Manual | TESTING/MATGEN/dlagsy.f(3) |
NAME
TESTING/MATGEN/dlagsy.f
SYNOPSIS
Functions/Subroutines
subroutine dlagsy (n, k, d, a, lda, iseed, work, info)
DLAGSY
Function/Subroutine Documentation
subroutine dlagsy (integer n, integer k, double precision, dimension( * ) d, double precision, dimension( lda, * ) a, integer lda, integer, dimension( 4 ) iseed, double precision, dimension( * ) work, integer info)
DLAGSY
Purpose:
DLAGSY 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 DOUBLE PRECISION array, dimension (N) The diagonal elements of the diagonal matrix D.
A
A is DOUBLE PRECISION 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 DOUBLE PRECISION 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 dlagsy.f.
Author
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