The Reverse Communication Interface

The basic structure of the reverse communication loop for the nonsymmetric drivers is similar to that for the symmetric driver with dsaupd replaced with dnaupd. See Figure A.1. The actions taken in dndrv1, dndrv2, dndrv3 and dndrv4 are exactly the same as those in dsdrv1 dsdrv2, dsdrv3 and dsdrv4. The matrix-vector operations required of each driver are listed in detail below. The operator OP defined in dndrv5 and dndrv6 is designed to accomplish spectral transformations for real nonsymmetric problems while computing exclusively in real arithmetic, the actions taken in these two drivers are completely different from dsdrv5 and dsdrv6.