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Updated: June 2017
 
 

chegv (3p)

Name

chegv - compute all the eigenvalues, and optionally, the eigenvectors of a complex generalized Hermitian-definite eigenproblem, of the form A*x=(lambda)*B*x, A*Bx=(lambda)*x, or B*A*x=(lambda)*x

Synopsis

SUBROUTINE CHEGV(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
LDWORK, WORK2, INFO)

CHARACTER*1 JOBZ, UPLO
COMPLEX A(LDA,*), B(LDB,*), WORK(*)
INTEGER ITYPE, N, LDA, LDB, LDWORK, INFO
REAL W(*), WORK2(*)

SUBROUTINE CHEGV_64(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
LDWORK, WORK2, INFO)

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




F95 INTERFACE
SUBROUTINE HEGV(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
LDWORK, WORK2, INFO)

CHARACTER(LEN=1) :: JOBZ, UPLO
COMPLEX, DIMENSION(:) :: WORK
COMPLEX, DIMENSION(:,:) :: A, B
INTEGER :: ITYPE, N, LDA, LDB, LDWORK, INFO
REAL, DIMENSION(:) :: W, WORK2

SUBROUTINE HEGV_64(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
LDWORK, WORK2, INFO)

CHARACTER(LEN=1) :: JOBZ, UPLO
COMPLEX, DIMENSION(:) :: WORK
COMPLEX, DIMENSION(:,:) :: A, B
INTEGER(8) :: ITYPE, N, LDA, LDB, LDWORK, INFO
REAL, DIMENSION(:) :: W, WORK2




C INTERFACE
#include <sunperf.h>

void chegv(int itype, char jobz, char uplo, int n, complex *a, int lda,
complex *b, int ldb, float *w, int *info);

void chegv_64(long itype, char jobz, char uplo,  long  n,  complex  *a,
long lda, complex *b, long ldb, float *w, long *info);

Description

Oracle Solaris Studio Performance Library                            chegv(3P)



NAME
       chegv  -  compute all the eigenvalues, and optionally, the eigenvectors
       of a complex generalized Hermitian-definite eigenproblem, of  the  form
       A*x=(lambda)*B*x, A*Bx=(lambda)*x, or B*A*x=(lambda)*x


SYNOPSIS
       SUBROUTINE CHEGV(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
             LDWORK, WORK2, INFO)

       CHARACTER*1 JOBZ, UPLO
       COMPLEX A(LDA,*), B(LDB,*), WORK(*)
       INTEGER ITYPE, N, LDA, LDB, LDWORK, INFO
       REAL W(*), WORK2(*)

       SUBROUTINE CHEGV_64(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
             LDWORK, WORK2, INFO)

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




   F95 INTERFACE
       SUBROUTINE HEGV(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
              LDWORK, WORK2, INFO)

       CHARACTER(LEN=1) :: JOBZ, UPLO
       COMPLEX, DIMENSION(:) :: WORK
       COMPLEX, DIMENSION(:,:) :: A, B
       INTEGER :: ITYPE, N, LDA, LDB, LDWORK, INFO
       REAL, DIMENSION(:) :: W, WORK2

       SUBROUTINE HEGV_64(ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK,
              LDWORK, WORK2, INFO)

       CHARACTER(LEN=1) :: JOBZ, UPLO
       COMPLEX, DIMENSION(:) :: WORK
       COMPLEX, DIMENSION(:,:) :: A, B
       INTEGER(8) :: ITYPE, N, LDA, LDB, LDWORK, INFO
       REAL, DIMENSION(:) :: W, WORK2




   C INTERFACE
       #include <sunperf.h>

       void chegv(int itype, char jobz, char uplo, int n, complex *a, int lda,
                 complex *b, int ldb, float *w, int *info);

       void chegv_64(long itype, char jobz, char uplo,  long  n,  complex  *a,
                 long lda, complex *b, long ldb, float *w, long *info);



PURPOSE
       chegv computes all the eigenvalues, and optionally, the eigenvectors of
       a complex generalized  Hermitian-definite  eigenproblem,  of  the  form
       A*x=(lambda)*B*x,  A*Bx=(lambda)*x,  or B*A*x=(lambda)*x.  Here A and B
       are assumed to be Hermitian and B is also
       positive definite.


ARGUMENTS
       ITYPE (input)
                 Specifies the problem type to be solved:
                 = 1:  A*x = (lambda)*B*x
                 = 2:  A*B*x = (lambda)*x
                 = 3:  B*A*x = (lambda)*x


       JOBZ (input)
                 = 'N':  Compute eigenvalues only;
                 = 'V':  Compute eigenvalues and eigenvectors.


       UPLO (input)
                 = 'U':  Upper triangles of A and B are stored;
                 = 'L':  Lower triangles of A and B are stored.


       N (input) The order of the matrices A and B.  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 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
                 matrix Z of eigenvectors.  The eigenvectors are normalized as
                 follows: if ITYPE = 1 or 2, Z**H*B*Z  =  I;  if  ITYPE  =  3,
                 Z**H*inv(B)*Z  =  I.   If  JOBZ = 'N', then on exit the upper
                 triangle (if UPLO='U') or the lower triangle (if UPLO='L') of
                 A, including the diagonal, is destroyed.


       LDA (input)
                 The leading dimension of the array A.  LDA >= max(1,N).


       B (input/output)
                 On  entry, the Hermitian positive definite matrix B.  If UPLO
                 = 'U', the leading N-by-N upper triangular part of B contains
                 the  upper  triangular  part of the matrix B.  If UPLO = 'L',
                 the leading N-by-N lower triangular part of  B  contains  the
                 lower triangular part of the matrix B.

                 On exit, if INFO <= N, the part of B containing the matrix is
                 overwritten by the triangular factor U or L from the Cholesky
                 factorization B = U**H*U or B = L*L**H.


       LDB (input)
                 The leading dimension of the array B.  LDB >= 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 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.


       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:  CPOTRF or CHEEV returned an error code:
                 <= N:  if INFO = i, CHEEV failed to converge; i  off-diagonal
                 elements of an intermediate tridiagonal form did not converge
                 to zero; > N:   if INFO = N + i, for 1 <= i <=  N,  then  the
                 leading  minor of order i of B is not positive definite.  The
                 factorization of B could not be completed and no  eigenvalues
                 or eigenvectors were computed.




                                  7 Nov 2015                         chegv(3P)