zlagsy.f3
Usage
Functions/Subroutines
subroutine zlagsy (n, k, d, a, lda, iseed, work, info)
ZLAGSY
Function/Subroutine Documentation
subroutine zlagsy (integer n, integer k, double precision, dimension( * ) d, complex*16, dimension( lda, * ) a, integer lda, integer, dimension( 4 ) iseed, complex*16, dimension( * ) work, integer info)
ZLAGSY
Purpose:
!> !> ZLAGSY generates a complex symmetric matrix A, by pre- and post- !> multiplying a real diagonal matrix D with a random unitary matrix: !> A = U*D*U**T. The semi-bandwidth may then be reduced to k by !> additional unitary 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 COMPLEX*16 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 COMPLEX*16 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 101 of file zlagsy.f.