Chpgvx + segmentation fault

Bonjour,
est-ce que quelqu'un pourrait m'expliquer pourquoi le code suivant renvoie une segmentation fault ? Je sais que pour effectuer le calcul suivant je peut utiliser chpgv mais ceci n'est qu'un exemple pour debugger car ensuite j'aurai besoin de calculer également certains vecteurs propres d'un sys. d'équation plus compliqué :-) Je crois que je vais faire une dépression :-)

program testchpgvx

complex, dimension(6) :: AP
complex, dimension(6) :: BP
integer :: N,M,INFO
real, dimension(6) :: W
complex, dimension(2*6) :: WORK
real, dimension(7*6) :: RWORK
integer, dimension(5*6) :: IWORK

N=6

AP=0
BP=0

AP(1)=1
AP(3)=1
AP(6)=1

BP(1)=1
BP(3)=1
BP(6)=1

call chpgvx(1,'N','A','U',N,AP,BP,0,M,W,1,WORK,RWORK,IWORK,INFO)


end program testchpgvx

Pour information ma ligne de compilation est la suivante :
gfortran main.f90 -o main /usr/lib/LAPACK/liblapack_gnu.a /usr/lib/BLAS/libblas_gnu.a

Merci infiniment !
Alex

ps. voici le man de chpgvx

CHPGVX(3S)

NAME

CHPGVX - compute selected eigenvalues and, optionally, 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 CHPGVX( ITYPE, JOBZ, RANGE, UPLO, N, AP, BP, VL, VU, IL, IU,
ABSTOL, M, W, Z, LDZ, WORK, RWORK, IWORK, IFAIL, INFO
)

CHARACTER JOBZ, RANGE, UPLO

INTEGER IL, INFO, ITYPE, IU, LDZ, M, N

REAL ABSTOL, VL, VU

INTEGER IFAIL( * ), IWORK( * )

REAL RWORK( * ), W( * )

COMPLEX AP( * ), BP( * ), WORK( * ), Z( LDZ, * )

IMPLEMENTATION

These routines are part of the SCSL Scientific Library and can be loaded
using either the -lscs or the -lscs_mp option. The -lscs_mp option
directs the linker to use the multi-processor version of the library.

When linking to SCSL with -lscs or -lscs_mp, the default integer size is
4 bytes (32 bits). Another version of SCSL is available in which integers
are 8 bytes (64 bits). This version allows the user access to larger
memory sizes and helps when porting legacy Cray codes. It can be loaded
by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
only one of the two versions; 4-byte integer and 8-byte integer library
calls cannot be mixed.

PURPOSE

CHPGVX computes selected eigenvalues and, optionally, 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, stored in packed format, and B is also positive
definite. Eigenvalues and eigenvectors can be selected by specifying
either a range of values or a range of indices for the desired
eigenvalues.

ARGUMENTS

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.

RANGE (input) CHARACTER*1
= 'A': all eigenvalues will be found;
= 'V': all eigenvalues in the half-open interval (VL,VU] will be
found; = 'I': the IL-th through IU-th eigenvalues will be found.

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.

AP (input/output) COMPLEX array, dimension (N*(N+1)/2)
On entry, the upper or lower triangle of the Hermitian matrix A,
packed columnwise in a linear array. The j-th column of A is
stored in the array AP as follows: if UPLO = 'U', AP(i + (j-
1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2*n-
j)/2) = A(i,j) for j<=i<=n.

On exit, the contents of AP are destroyed.

BP (input/output) COMPLEX array, dimension (N*(N+1)/2)
On entry, the upper or lower triangle of the Hermitian matrix B,
packed columnwise in a linear array. The j-th column of B is
stored in the array BP as follows: if UPLO = 'U', BP(i + (j-
1)*j/2) = B(i,j) for 1<=i<=j; if UPLO = 'L', BP(i + (j-1)*(2*n-
j)/2) = B(i,j) for j<=i<=n.

On exit, the triangular factor U or L from the Cholesky
factorization B = U**H*U or B = L*L**H, in the same storage
format as B.

VL (input) REAL
VU (input) REAL If RANGE='V', the lower and upper bounds of
the interval to be searched for eigenvalues. VL < VU. Not
referenced if RANGE = 'A' or 'I'.

IL (input) INTEGER
IU (input) INTEGER If RANGE='I', the indices (in ascending
order) of the smallest and largest eigenvalues to be returned. 1
<= IL <= IU <= N, if N > 0; IL = 1 and IU = 0 if N = 0. Not
referenced if RANGE = 'A' or 'V'.

ABSTOL (input) REAL
The absolute error tolerance for the eigenvalues. An approximate
eigenvalue is accepted as converged when it is determined to lie
in an interval [a,b] of width less than or equal to
ABSTOL + EPS * max( |a|,|b| ) ,

where EPS is the machine precision. If ABSTOL is less than or
equal to zero, then EPS*|T| will be used in its place, where
|T| is the 1-norm of the tridiagonal matrix obtained by reducing
AP to tridiagonal form.

Eigenvalues will be computed most accurately when ABSTOL is set
to twice the underflow threshold 2*SLAMCH('S'), not zero. If
this routine returns with INFO>0, indicating that some
eigenvectors did not converge, try setting ABSTOL to
2*SLAMCH('S').

M (output) INTEGER
The total number of eigenvalues found. 0 <= M <= N. If RANGE =
'A', M = N, and if RANGE = 'I', M = IU-IL+1.

W (output) REAL array, dimension (N)
On normal exit, the first M elements contain the selected
eigenvalues in ascending order.

Z (output) COMPLEX array, dimension (LDZ, N)
If JOBZ = 'N', then Z is not referenced. If JOBZ = 'V', then if
INFO = 0, the first M columns of Z contain the orthonormal
eigenvectors of the matrix A corresponding to the selected
eigenvalues, with the i-th column of Z holding the eigenvector
associated with W(i). 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 an eigenvector fails to converge, then that column of Z
contains the latest approximation to the eigenvector, and the
index of the eigenvector is returned in IFAIL. Note: the user
must ensure that at least max(1,M) columns are supplied in the
array Z; if RANGE = 'V', the exact value of M is not known in
advance and an upper bound must be used.

LDZ (input) INTEGER
The leading dimension of the array Z. LDZ >= 1, and if JOBZ =
'V', LDZ >= max(1,N).

WORK (workspace) COMPLEX array, dimension (2*N)

RWORK (workspace) REAL array, dimension (7*N)

IWORK (workspace) INTEGER array, dimension (5*N)

IFAIL (output) INTEGER array, dimension (N)
If JOBZ = 'V', then if INFO = 0, the first M elements of IFAIL
are zero. If INFO > 0, then IFAIL contains the indices of the
eigenvectors that failed to converge. If JOBZ = 'N', then IFAIL
is not referenced.

INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
> 0: CPPTRF or CHPEVX returned an error code:
<= N: if INFO = i, CHPEVX failed to converge; i eigenvectors
failed to converge. Their indices are stored in array IFAIL. >
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.