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LAPACK: Linear Algebra PACKage
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slagsy.f File Reference

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Functions/Subroutines

subroutine slagsy (N, K, D, A, LDA, ISEED, WORK, INFO)
 SLAGSY More...
 

Function/Subroutine Documentation

subroutine slagsy ( integer  N,
integer  K,
real, dimension( * )  D,
real, dimension( lda, * )  A,
integer  LDA,
integer, dimension( 4 )  ISEED,
real, dimension( * )  WORK,
integer  INFO 
)

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
[in]N
          N is INTEGER
          The order of the matrix A.  N >= 0.
[in]K
          K is INTEGER
          The number of nonzero subdiagonals within the band of A.
          0 <= K <= N-1.
[in]D
          D is REAL array, dimension (N)
          The diagonal elements of the diagonal matrix D.
[out]A
          A is REAL array, dimension (LDA,N)
          The generated n by n symmetric matrix A (the full matrix is
          stored).
[in]LDA
          LDA is INTEGER
          The leading dimension of the array A.  LDA >= N.
[in,out]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.
[out]WORK
          WORK is REAL array, dimension (2*N)
[out]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.
Date
November 2011

Definition at line 102 of file slagsy.f.

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