Templates and Driver Routines

  A collection of simple driver routines was described in Chapter 2. This appendix describes a more sophisticated set of example drivers that illustrate all of the available computational   modes and shift-invert strategies available within ARPACK. All aspects of solving standard or generalized eigenvalue problems, as well as computing a partial SVD are covered here. As with the simple drivers, these have been designed to use as templates that may be modified for a specific user application. These drivers can be found in the following subdirectories in the EXAMPLES directory. The contents of this EXAMPLES directory are:

SYM Real symmetric eigenvalue problems,

NONSYM Real non-symmetric eigenvalue problems,

COMPLEX Complex eigenvalue problems,

BAND Eigenvalue problems in which matrices are stored in LAPACK band form,

SVD Singular value decomposition (SVD) problems.

Each driver illustrates how variables are declared and used, how the reverse communication communication interface is used within a particular computational mode, and how to check the accuracy of the computed results.

This Appendix provides some guidance on deciding which driver to select and how to use it effectively. In order to aid the process of building a user's application code from these drivers, we discuss the necessary steps to be followed to use these drivers as templates and modify them appropriately. These steps may be summarized as follows:

• Selecting an appropriate driver.
• Identifying and constructing the linear operator OP and the matrix B used in a driver.
• Substituting the constructed linear operator OP and the matrix B in the reverse communication interface.
• Modifying the problem dependent variables.
• Checking the accuracy of the computed results.

This procedure is discussed in  A.1-A.3 for the solution of symmetric, nonsymmetric and complex arithmetic eigenvalue problems with ARPACK. Each case is discussed independently, so there is considerable repetition. The user is encouraged to select the section that discusses the specific problem type of interest.