• NAME
• SYNOPSIS
• F95 INTERFACE
• C INTERFACE
• PURPOSE
• ARGUMENTS

NAME

cheev - compute all eigenvalues and, optionally, eigenvectors of a complex Hermitian matrix A

SYNOPSIS

  SUBROUTINE CHEEV( JOBZ, UPLO, N, A, LDA, W, WORK, LDWORK, WORK2, 
 *      INFO)
  CHARACTER * 1 JOBZ, UPLO
  COMPLEX A(LDA,*), WORK(*)
  INTEGER N, LDA, LDWORK, INFO
  REAL W(*), WORK2(*)

  SUBROUTINE CHEEV_64( JOBZ, UPLO, N, A, LDA, W, WORK, LDWORK, WORK2, 
 *      INFO)
  CHARACTER * 1 JOBZ, UPLO
  COMPLEX A(LDA,*), WORK(*)
  INTEGER*8 N, LDA, LDWORK, INFO
  REAL W(*), WORK2(*)

F95 INTERFACE

  SUBROUTINE HEEV( JOBZ, UPLO, [N], A, [LDA], W, [WORK], [LDWORK], 
 *       [WORK2], [INFO])
  CHARACTER(LEN=1) :: JOBZ, UPLO
  COMPLEX, DIMENSION(:) :: WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER :: N, LDA, LDWORK, INFO
  REAL, DIMENSION(:) :: W, WORK2

  SUBROUTINE HEEV_64( JOBZ, UPLO, [N], A, [LDA], W, [WORK], [LDWORK], 
 *       [WORK2], [INFO])
  CHARACTER(LEN=1) :: JOBZ, UPLO
  COMPLEX, DIMENSION(:) :: WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER(8) :: N, LDA, LDWORK, INFO
  REAL, DIMENSION(:) :: W, WORK2

C INTERFACE

#include <sunperf.h>

void cheev(char jobz, char uplo, int n, complex *a, int lda, float *w, int *info);

void cheev_64(char jobz, char uplo, long n, complex *a, long lda, float *w, long *info);

PURPOSE

cheev computes all eigenvalues and, optionally, eigenvectors of a complex Hermitian 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 Hermitian matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular 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 diagonal, 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(1,2*N-1). For optimal efficiency, LDWORK > = (NB+1)*N, where NB is the blocksize for CHETRD returned by ILAENV.

  If LDWORK = -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 LDWORK is issued by XERBLA.

• 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.