diff options
Diffstat (limited to 'SRC/chegvx.f')
| -rw-r--r-- | SRC/chegvx.f | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/SRC/chegvx.f b/SRC/chegvx.f index 2171a5a3..34e0ea7c 100644 --- a/SRC/chegvx.f +++ b/SRC/chegvx.f @@ -73,13 +73,14 @@ *> = 'V': all eigenvalues in the half-open interval (VL,VU] *> will be found. *> = 'I': the IL-th through IU-th eigenvalues will be found. +*> \endverbatim +*> *> \param[in] UPLO *> \verbatim *> UPLO is CHARACTER*1 *> = 'U': Upper triangles of A and B are stored; *> = 'L': Lower triangles of A and B are stored. *> \endverbatim -*> \endverbatim *> *> \param[in] N *> \verbatim @@ -95,8 +96,7 @@ *> 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. -*> \endverbatim -*> \verbatim +*> *> On exit, the lower triangle (if UPLO='L') or the upper *> triangle (if UPLO='U') of A, including the diagonal, is *> destroyed. @@ -116,8 +116,7 @@ *> 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. -*> \endverbatim -*> \verbatim +*> *> 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. @@ -132,27 +131,33 @@ *> \param[in] VL *> \verbatim *> VL is REAL +*> \endverbatim +*> *> \param[in] VU *> \verbatim *> VU is REAL +*> \endverbatim +*> \verbatim *> 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'. *> \endverbatim -*> \endverbatim *> *> \param[in] IL *> \verbatim *> IL is INTEGER +*> \endverbatim +*> *> \param[in] IU *> \verbatim *> IU is INTEGER +*> \endverbatim +*> \verbatim *> 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'. *> \endverbatim -*> \endverbatim *> *> \param[in] ABSTOL *> \verbatim @@ -161,19 +166,16 @@ *> 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 -*> \endverbatim -*> \verbatim +*> *> ABSTOL + EPS * max( |a|,|b| ) , -*> \endverbatim -*> \verbatim +*> *> 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 C to tridiagonal form, where C is the symmetric *> matrix of the standard symmetric problem to which the *> generalized problem is transformed. -*> \endverbatim -*> \verbatim +*> *> 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 @@ -206,8 +208,7 @@ *> The eigenvectors are normalized as follows: *> if ITYPE = 1 or 2, Z**T*B*Z = I; *> if ITYPE = 3, Z**T*inv(B)*Z = I. -*> \endverbatim -*> \verbatim +*> *> 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. |