dpttrf (l) - Linux Manuals
dpttrf: computes the L*D*Laq factorization of a real symmetric positive definite tridiagonal matrix A
Command to display dpttrf
manual in Linux: $ man l dpttrf
NAME
DPTTRF - computes the L*D*Laq factorization of a real symmetric positive definite tridiagonal matrix A
SYNOPSIS
- SUBROUTINE DPTTRF(
-
N, D, E, INFO )
-
INTEGER
INFO, N
-
DOUBLE
PRECISION D( * ), E( * )
PURPOSE
DPTTRF computes the L*D*Laq factorization of a real symmetric
positive definite tridiagonal matrix A. The factorization may also
be regarded as having the form A = Uaq*D*U.
ARGUMENTS
- N (input) INTEGER
-
The order of the matrix A. N >= 0.
- D (input/output) DOUBLE PRECISION array, dimension (N)
-
On entry, the n diagonal elements of the tridiagonal matrix
A. On exit, the n diagonal elements of the diagonal matrix
D from the L*D*Laq factorization of A.
- E (input/output) DOUBLE PRECISION array, dimension (N-1)
-
On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix A. On exit, the (n-1) subdiagonal elements of the
unit bidiagonal factor L from the L*D*Laq factorization of A.
E can also be regarded as the superdiagonal of the unit
bidiagonal factor U from the Uaq*D*U factorization of A.
- INFO (output) INTEGER
-
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
> 0: if INFO = k, the leading minor of order k is not
positive definite; if k < N, the factorization could not
be completed, while if k = N, the factorization was
completed, but D(N) <= 0.
Pages related to dpttrf
- dpttrf (3)
- dpttrs (l) - solves a tridiagonal system of the form A * X = B using the L*D*Laq factorization of A computed by DPTTRF
- dptts2 (l) - solves a tridiagonal system of the form A * X = B using the L*D*Laq factorization of A computed by DPTTRF
- dptcon (l) - computes the reciprocal of the condition number (in the 1-norm) of a real symmetric positive definite tridiagonal matrix using the factorization A = L*D*L**T or A = U**T*D*U computed by DPTTRF
- dpteqr (l) - computes all eigenvalues and, optionally, eigenvectors of a symmetric positive definite tridiagonal matrix by first factoring the matrix using DPTTRF, and then calling DBDSQR to compute the singular values of the bidiagonal factor
- dptrfs (l) - improves the computed solution to a system of linear equations when the coefficient matrix is symmetric positive definite and tridiagonal, and provides error bounds and backward error estimates for the solution
- dptsv (l) - computes the solution to a real system of linear equations A*X = B, where A is an N-by-N symmetric positive definite tridiagonal matrix, and X and B are N-by-NRHS matrices
- dptsvx (l) - uses the factorization A = L*D*L**T to compute the solution to a real system of linear equations A*X = B, where A is an N-by-N symmetric positive definite tridiagonal matrix and X and B are N-by-NRHS matrices