dsyev(3P) Sun Performance Library dsyev(3P)NAMEdsyev - compute all eigenvalues and, optionally, eigenvectors of a real
symmetric matrix A
SYNOPSIS
SUBROUTINE DSYEV(JOBZ, UPLO, N, A, LDA, W, WORK, LDWORK, INFO)
CHARACTER * 1 JOBZ, UPLO
INTEGER N, LDA, LDWORK, INFO
DOUBLE PRECISION A(LDA,*), W(*), WORK(*)
SUBROUTINE DSYEV_64(JOBZ, UPLO, N, A, LDA, W, WORK, LDWORK, INFO)
CHARACTER * 1 JOBZ, UPLO
INTEGER*8 N, LDA, LDWORK, INFO
DOUBLE PRECISION A(LDA,*), W(*), WORK(*)
F95 INTERFACE
SUBROUTINE SYEV(JOBZ, UPLO, N, A, [LDA], W, [WORK], [LDWORK], [INFO])
CHARACTER(LEN=1) :: JOBZ, UPLO
INTEGER :: N, LDA, LDWORK, INFO
REAL(8), DIMENSION(:) :: W, WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE SYEV_64(JOBZ, UPLO, N, A, [LDA], W, [WORK], [LDWORK],
[INFO])
CHARACTER(LEN=1) :: JOBZ, UPLO
INTEGER(8) :: N, LDA, LDWORK, INFO
REAL(8), DIMENSION(:) :: W, WORK
REAL(8), DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void dsyev(char jobz, char uplo, int n, double *a, int lda, double *w,
int *info);
void dsyev_64(char jobz, char uplo, long n, double *a, long lda, double
*w, long *info);
PURPOSEdsyev computes all eigenvalues and, optionally, eigenvectors of a real
symmetric matrix A.
ARGUMENTS
JOBZ (input)
= 'N': Compute eigenvalues only;
= 'V': Compute eigenvalues and eigenvectors.
UPLO (input)
= 'U': Upper triangle of A is stored;
= 'L': Lower triangle of A is stored.
N (input) The order of the matrix A. N >= 0.
A (input/output)
On entry, the symmetric matrix A. If UPLO = 'U', the leading
N-by-N upper triangular part of A contains the upper triangu‐
lar part of the matrix A. If UPLO = 'L', the leading N-by-N
lower triangular part of A contains the lower triangular part
of the matrix A. On exit, if JOBZ = 'V', then if INFO = 0, A
contains the orthonormal eigenvectors of the matrix A. If
JOBZ = 'N', then on exit the lower triangle (if UPLO='L') or
the upper triangle (if UPLO='U') of A, including the diago‐
nal, is destroyed.
LDA (input)
The leading dimension of the array A. LDA >= max(1,N).
W (output)
If INFO = 0, the eigenvalues in ascending order.
WORK (workspace)
On exit, if INFO = 0, WORK(1) returns the optimal LDWORK.
LDWORK (input)
The length of the array WORK. LDWORK >= max(1,3*N-1). For
optimal efficiency, LDWORK >= (NB+2)*N, where NB is the
blocksize for DSYTRD returned by ILAENV.
If LDWORK = -1, then a workspace query is assumed; the rou‐
tine 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 LDWORK is issued by XERBLA.
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: if INFO = i, the algorithm failed to converge; i off-
diagonal elements of an intermediate tridiagonal form did not
converge to zero.
6 Mar 2009 dsyev(3P)