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Diffstat (limited to 'math/arpack/DESCR')
| -rw-r--r-- | math/arpack/DESCR | 58 |
1 files changed, 35 insertions, 23 deletions
diff --git a/math/arpack/DESCR b/math/arpack/DESCR index 3205bcda348..ded552c3db2 100644 --- a/math/arpack/DESCR +++ b/math/arpack/DESCR @@ -1,23 +1,35 @@ -ARPACK is a collection of Fortran77 subroutines designed to solve large scale -eigenvalue problems. The package is designed to compute a few eigenvalues and -corresponding eigenvectors of a general n by n matrix A. It is most appropriate -for large sparse or structured matrices A where structured means that a -matrix-vector product w <- Av requires order n rather than the usual order n**2 -floating point operations. This software is based upon an algorithmic variant of -the Arnoldi process called the Implicitly Restarted Arnoldi Method (IRAM). When -the matrix A is symmetric it reduces to a variant of the Lanczos process called -the Implicitly Restarted Lanczos Method (IRLM). These variants may be viewed as -a synthesis of the Arnoldi/Lanczos process with the Implicitly Shifted QR -technique that is suitable for large scale problems. For many standard problems, -a matrix factorization is not required. Only the action of the matrix on a -vector is needed. ARPACK software is capable of solving large scale symmetric, -nonsymmetric, and generalized eigenproblems from significant application areas. -The software is designed to compute a few (k) eigenvalues with user specified -features such as those of largest real part or largest magnitude. Storage -requirements are on the order of n*k locations. No auxiliary storage is -required. A set of Schur basis vectors for the desired k-dimensional eigen-space -is computed which is numerically orthogonal to working precision. Numerically accurate eigenvectors are available on request. Important Features: - o Reverse Communication Interface. - o Single and Double Precision Real Arithmetic Versions for Symmetric, - Non-symmetric, Standard or Generalized Problems. - ...and more! +ARPACK is a collection of Fortran77 subroutines designed to solve large +scale eigenvalue problems. + +The package is designed to compute a few eigenvalues and corresponding +eigenvectors of a general n by n matrix A. It is most appropriate for large +sparse or structured matrices A where structured means that a matrix-vector +product w <- Av requires order n rather than the usual order n**2 floating +point operations. This software is based upon an algorithmic variant of the +Arnoldi process called the Implicitly Restarted Arnoldi Method (IRAM). When +the matrix A is symmetric it reduces to a variant of the Lanczos process +called the Implicitly Restarted Lanczos Method (IRLM). These variants may be +viewed as a synthesis of the Arnoldi/Lanczos process with the Implicitly +Shifted QR technique that is suitable for large scale problems. For many +standard problems, a matrix factorization is not required. Only the action +of the matrix on a vector is needed. ARPACK software is capable of solving +large scale symmetric, nonsymmetric, and generalized eigenproblems from +significant application areas. The software is designed to compute a few (k) +eigenvalues with user specified features such as those of largest real part +or largest magnitude. Storage requirements are on the order of n*k locations. +No auxiliary storage is required. A set of Schur basis vectors for the desired +k-dimensional eigen-space is computed which is numerically orthogonal to working +precision. Numerically accurate eigenvectors are available on request. + +Important Features: + + o Reverse Communication Interface. + o Single and Double Precision Real Arithmetic Versions for Symmetric, + Non-symmetric, Standard or Generalized Problems. + o Single and Double Precision Complex Arithmetic Versions for Standard + or Generalized Problems. + o Routines for Banded Matrices - Standard or Generalized Problems. + o Routines for The Singular Value Decomposition. + o Example driver routines that may be used as templates to implement + numerous Shift-Invert strategies for all problem types, data types + and precision. |