diff options
Diffstat (limited to 'SRC/cheevx.f')
| -rw-r--r-- | SRC/cheevx.f | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/SRC/cheevx.f b/SRC/cheevx.f index 2073733b..f2d41f68 100644 --- a/SRC/cheevx.f +++ b/SRC/cheevx.f @@ -131,24 +131,20 @@ *> 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 A to tridiagonal form. -*> \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 *> eigenvectors did not converge, try setting ABSTOL to *> 2*SLAMCH('S'). -*> \endverbatim -*> \verbatim +*> *> See "Computing Small Singular Values of Bidiagonal Matrices *> with Guaranteed High Relative Accuracy," by Demmel and *> Kahan, LAPACK Working Note #3. @@ -205,8 +201,7 @@ *> For optimal efficiency, LWORK >= (NB+1)*N, *> where NB is the max of the blocksize for CHETRD and for *> CUNMTR as returned by ILAENV. -*> \endverbatim -*> \verbatim +*> *> 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 |