Identify OP and B for the Driver

Once a driver is chosen, the next step is to identify OP and B associated with that driver. Eigenvalues of OP are computed by the computational routine dnaupd. These eigenvalues are converted to those of ${\bf A}$ or in the post-processing routine dseupd. The Arnoldi vectors generated by dnaupd are B-orthonormal. It is very important to construct the matrix vector operations

correctly. Table A.5 summarizes the operators OP and B used by the drivers. The notation and is used to denote the real and imaginary parts of a complex matrix, respectively.

 

DRIVER OP B

$${\bf A}$$ dndrv1 dndrv2

$${\bf M}$$ dndrv3

$${\bf M}$$ dndrv4

$${\bf M}$$ dndrv5

$${\bf M}$$ dndrv6

Because of the reverse communication interface of ARPACK, the construction of

is left completely to the user. This means that the user is free to choose any convenient data structure  for the matrix representation. If the matrix is not available, the user is free to express the action of the matrix on a vector through a subroutine call or a code segment.