dsyev (l)  Linux Manuals
dsyev: computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A
Command to display dsyev
manual in Linux: $ man l dsyev
NAME
DSYEV  computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A
SYNOPSIS
 SUBROUTINE DSYEV(

JOBZ, UPLO, N, A, LDA, W, WORK, LWORK, INFO )

CHARACTER
JOBZ, UPLO

INTEGER
INFO, LDA, LWORK, N

DOUBLE
PRECISION A( LDA, * ), W( * ), WORK( * )
PURPOSE
DSYEV computes all eigenvalues and, optionally, eigenvectors of a
real symmetric matrix A.
ARGUMENTS
 JOBZ (input) CHARACTER*1

= aqNaq: Compute eigenvalues only;
= aqVaq: Compute eigenvalues and eigenvectors.
 UPLO (input) CHARACTER*1

= aqUaq: Upper triangle of A is stored;
= aqLaq: Lower triangle of A is stored.
 N (input) INTEGER

The order of the matrix A. N >= 0.
 A (input/output) DOUBLE PRECISION array, dimension (LDA, N)

On entry, the symmetric matrix A. If UPLO = aqUaq, the
leading NbyN upper triangular part of A contains the
upper triangular part of the matrix A. If UPLO = aqLaq,
the leading NbyN lower triangular part of A contains
the lower triangular part of the matrix A.
On exit, if JOBZ = aqVaq, then if INFO = 0, A contains the
orthonormal eigenvectors of the matrix A.
If JOBZ = aqNaq, then on exit the lower triangle (if UPLO=aqLaq)
or the upper triangle (if UPLO=aqUaq) of A, including the
diagonal, is destroyed.
 LDA (input) INTEGER

The leading dimension of the array A. LDA >= max(1,N).
 W (output) DOUBLE PRECISION array, dimension (N)

If INFO = 0, the eigenvalues in ascending order.
 WORK (workspace/output) DOUBLE PRECISION array, dimension (MAX(1,LWORK))

On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
 LWORK (input) INTEGER

The length of the array WORK. LWORK >= max(1,3*N1).
For optimal efficiency, LWORK >= (NB+2)*N,
where NB is the blocksize for DSYTRD returned by ILAENV.
If LWORK = 1, then a workspace query is assumed; the routine
only calculates the optimal size of the WORK array, returns
this value as the first entry of the WORK array, and no error
message related to LWORK is issued by XERBLA.
 INFO (output) INTEGER

= 0: successful exit
< 0: if INFO = i, the ith argument had an illegal value
> 0: if INFO = i, the algorithm failed to converge; i
offdiagonal elements of an intermediate tridiagonal
form did not converge to zero.
Pages related to dsyev
 dsyev (3)
 dsyevd (l)  computes all eigenvalues and, optionally, eigenvectors of a real symmetric matrix A
 dsyevr (l)  computes selected eigenvalues and, optionally, eigenvectors of a real symmetric matrix A
 dsyevx (l)  computes selected eigenvalues and, optionally, eigenvectors of a real symmetric matrix A
 dsyequb (l)  computes row and column scalings intended to equilibrate a symmetric matrix A and reduce its condition number (with respect to the twonorm)
 dsycon (l)  estimates the reciprocal of the condition number (in the 1norm) of a real symmetric matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by DSYTRF
 dsygs2 (l)  reduces a real symmetricdefinite generalized eigenproblem to standard form
 dsygst (l)  reduces a real symmetricdefinite generalized eigenproblem to standard form
 dsygv (l)  computes all the eigenvalues, and optionally, the eigenvectors of a real generalized symmetricdefinite eigenproblem, of the form A*x=(lambda)*B*x, A*Bx=(lambda)*x, or B*A*x=(lambda)*x