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Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
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chegv(l) |
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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
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SUBROUTINE CHEGV( |
ITYPE, JOBZ, UPLO, N, A, LDA, B, LDB, W, WORK, LWORK, RWORK, INFO ) | ||
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CHARACTER |
JOBZ, UPLO | ||
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INTEGER |
INFO, ITYPE, LDA, LDB, LWORK, N | ||
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REAL |
RWORK( * ), W( * ) | ||
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COMPLEX |
A( LDA, * ), B( LDB, * ), WORK( * ) |
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.
ITYPE (input) INTEGER
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) CHARACTER*1
= ’N’: Compute
eigenvalues only;
= ’V’: Compute eigenvalues and eigenvectors.
UPLO (input) CHARACTER*1
= ’U’: Upper
triangles of A and B are stored;
= ’L’: Lower triangles of A and B are
stored.
N (input) INTEGER
The order of the matrices A and B. N >= 0.
A (input/output) COMPLEX array, dimension (LDA, N)
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 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) INTEGER
The leading dimension of the array A. LDA >= max(1,N).
B (input/output) COMPLEX array, dimension (LDB, N)
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) INTEGER
The leading dimension of the array B. LDB >= max(1,N).
W (output) REAL array, dimension (N)
If INFO = 0, the eigenvalues in ascending order.
WORK (workspace/output) COMPLEX array, dimension (LWORK)
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK (input) INTEGER
The length of the array WORK. LWORK >= max(1,2*N-1). For optimal efficiency, LWORK >= (NB+1)*N, where NB is the blocksize for CHETRD 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.
RWORK (workspace) REAL array,
dimension (max(1, 3*N-2))
INFO (output) INTEGER
= 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.
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chegv(l) | |