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Driver `dndrv1` solves the standard eigenvalue problem

This mode only requires matrix vector products with This driver will compute the eigenvalues of largest
or smallest magnitude, largest or smallest real part, largest
or smallest imaginary part depending on the setting of `which`.
It is most appropriate for computing extremal, non-clustered eigenvalues
(here extremal means extreme points of the convex hull of the spectrum).
In particular, if the operation can be easily formed,
then using the shift-invert driver `dndrv2` with zero shift is
certainly a far more effective way to compute eigenvalues of the
smallest magnitude.

*Chao Yang*

*11/7/1997*