chbev(3P) Sun Performance Library chbev(3P)NAMEchbev - compute all the eigenvalues and, optionally, eigenvectors of a
complex Hermitian band matrix A
SYNOPSIS
SUBROUTINE CHBEV(JOBZ, UPLO, N, KD, A, LDA, W, Z, LDZ, WORK,
WORK2, INFO)
CHARACTER * 1 JOBZ, UPLO
COMPLEX A(LDA,*), Z(LDZ,*), WORK(*)
INTEGER N, KD, LDA, LDZ, INFO
REAL W(*), WORK2(*)
SUBROUTINE CHBEV_64(JOBZ, UPLO, N, KD, A, LDA, W, Z, LDZ, WORK,
WORK2, INFO)
CHARACTER * 1 JOBZ, UPLO
COMPLEX A(LDA,*), Z(LDZ,*), WORK(*)
INTEGER*8 N, KD, LDA, LDZ, INFO
REAL W(*), WORK2(*)
F95 INTERFACE
SUBROUTINE HBEV(JOBZ, UPLO, [N], KD, A, [LDA], W, Z, [LDZ], [WORK],
[WORK2], [INFO])
CHARACTER(LEN=1) :: JOBZ, UPLO
COMPLEX, DIMENSION(:) :: WORK
COMPLEX, DIMENSION(:,:) :: A, Z
INTEGER :: N, KD, LDA, LDZ, INFO
REAL, DIMENSION(:) :: W, WORK2
SUBROUTINE HBEV_64(JOBZ, UPLO, [N], KD, A, [LDA], W, Z, [LDZ],
[WORK], [WORK2], [INFO])
CHARACTER(LEN=1) :: JOBZ, UPLO
COMPLEX, DIMENSION(:) :: WORK
COMPLEX, DIMENSION(:,:) :: A, Z
INTEGER(8) :: N, KD, LDA, LDZ, INFO
REAL, DIMENSION(:) :: W, WORK2
C INTERFACE
#include <sunperf.h>
void chbev(char jobz, char uplo, int n, int kd, complex *a, int lda,
float *w, complex *z, int ldz, int *info);
void chbev_64(char jobz, char uplo, long n, long kd, complex *a, long
lda, float *w, complex *z, long ldz, long *info);
PURPOSEchbev computes all the eigenvalues and, optionally, eigenvectors of a
complex Hermitian band 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.
KD (input)
The number of superdiagonals of the matrix A if UPLO = 'U',
or the number of subdiagonals if UPLO = 'L'. KD >= 0.
A (input/output)
On entry, the upper or lower triangle of the Hermitian band
matrix A, stored in the first KD+1 rows of the array. The j-
th column of A is stored in the j-th column of the array A as
follows: if UPLO = 'U', A(kd+1+i-j,j) = A(i,j) for max(1,j-
kd)<=i<=j; if UPLO = 'L', A(1+i-j,j) = A(i,j) for
j<=i<=min(n,j+kd).
On exit, A is overwritten by values generated during the
reduction to tridiagonal form. If UPLO = 'U', the first
superdiagonal and the diagonal of the tridiagonal matrix T
are returned in rows KD and KD+1 of A, and if UPLO = 'L', the
diagonal and first subdiagonal of T are returned in the first
two rows of A.
LDA (input)
The leading dimension of the array A. LDA >= KD + 1.
W (output)
If INFO = 0, the eigenvalues in ascending order.
Z (output)
If JOBZ = 'V', then if INFO = 0, Z contains the orthonormal
eigenvectors of the matrix A, with the i-th column of Z hold‐
ing the eigenvector associated with W(i). If JOBZ = 'N',
then Z is not referenced.
LDZ (input)
The leading dimension of the array Z. LDZ >= 1, and if JOBZ
= 'V', LDZ >= max(1,N).
WORK (workspace)
dimension(N)
WORK2 (workspace)
dimension(max(1,3*N-2))
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 chbev(3P)