LAPACK, the Linear Algebra PACKage, is a software library for numerical computing written in Fortran 77. It provides routines for solving systems of simultaneous linear equations, least-squares solutions of linear systems of equations, eigenvalue problems, Householder transformation to implement QR decomposition on a matrix and singular value problems. Lapack95 uses features of Fortran 95 to simplify the interface of the routines.
LAPACK is designed to run on modern high performance vector computers with shared memory.
It depends on the Basic Linear Algebra Subprograms BLAS and has been extended to run on distributed systems with ScaLAPACK
LAPACK has largely superceded the Eigenvalue routines from EISPACK, and the linear equations and linear least-squares problems from LINPACK.
Here is a table Matrix types in the LAPACK naming scheme
| Name
| Description
|
| BD
| Bidiagonal matrix
|
| DI
| Diagonal matrix
|
| GB
| Band matrix
|
| GE
| Matrix (i.e., unsymmetric, in some
cases rectangular)
|
| GG
| general matrices, generalized problem (i.e., a pair of general matrices)
|
| GT
| Tridiagonal Matrix General Matrix
|
| HB
| (complex) Hermitian matrix Band matrix
|
| HE
| (complex) Hermitian matrix
|
| HG
| upper Hessenberg matrix, generalized problem (i.e a Hessenberg and a Triangular matrix)
|
| HP
| (complex) Hermitian matrix, Packed storage matrix
|
| HS
| upper Hessenberg matrix
|
| OP
| (real) Orthogonal matrix, Packed storage matrix
|
| OR
| (real) Orthogonal matrix
|
| PB
| Symmetric matrix or Hermitian matrix positive definite band
|
| PO
| Symmetric matrix or Hermitian matrix positive definite
|
| PP
| Symmetric matrix or Hermitian matrix positive definite, Packed storage matrix
|
| PT
| Symmetric matrix or Hermitian matrix positive definite Tridiagonal matrix
|
| SB
| (real) Symmetric matrix Band matrix
|
| SP
| Symmetric matrix, Packed storage matrix
|
| ST
| (real) Symmetric matrix Tridiagonal matrix
|
| SY
| Symmetric matrix
|
| TB
| Triangular matrix Band matrix
|
| TG
| triangular matrices, generalized problem (i.e., a pair of triangular matrices)
|
| TP
| Triangular matrix, Packed storage matrix
|
| TR
| Triangular matrix (or in some cases quasi-triangular)
|
| TZ
| Trapezoidal matrix
|
| UN
| (complex) Unitary matrix
|
| UP
| (complex) Unitary matrix, Packed storage matrix
|
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