feast_initinitializes a data structure for the NAG FEAST suite of functions consisting of
feast_free(). It is used to find some of the eigenvalues, and the corresponding eigenvectors, of a standard, generalized or polynomial eigenvalue problem.
The suite of functions is suitable for the solution of large, sparse eigenproblems where only those eigenvalues within a selected region of the complex plane are required.
For full information please refer to the NAG Library document for f12ja
Holds a handle to the internal data structure used by the NAG FEAST suite.
The NAG FEAST suite of functions is designed to calculate some of the eigenvalues, , and the corresponding eigenvectors, , of a standard eigenvalue problem , a generalized eigenvalue problem , where and are large and sparse, or a polynomial eigenvalue problem . It can also be used to find eigenvalues/eigenvectors of smaller scale dense problems. The NAG FEAST suite is based on the FEAST library, using contour integration to find the eigenvalues within a contour in the complex plane.
feast_initis a setup function which must be called before the option setting function
feast_option(), before the contour definition functions
feast_custom_contour(), and before the reverse communication solvers
This setup function initializes the handle to a data structure used internally by the NAG FEAST suite and sets (to their default values) all options that can be set by you via the option setting function
feast_option(). For details of the options available and how to set them see Other Parameters for feast_option. When the handle is no longer needed,
feast_free()must be called to destroy it and deallocate all the allocated memory and data within.
Polizzi, E, 2009, Density-Matrix-Based Algorithms for Solving Eigenvalue Problems, Phys. Rev. B. (79), 115112