cgttrf.f(3) LAPACK cgttrf.f(3)
subroutine cgttrf (N, DL, D, DU, DU2, IPIV, INFO)
subroutine cgttrf (integerN, complex, dimension( * )DL, complex, dimension( * )D, complex,
dimension( * )DU, complex, dimension( * )DU2, integer, dimension( * )IPIV, integerINFO)
CGTTRF computes an LU factorization of a complex tridiagonal matrix A
using elimination with partial pivoting and row interchanges.
The factorization has the form
A = L * U
where L is a product of permutation and unit lower bidiagonal
matrices and U is upper triangular with nonzeros in only the main
diagonal and first two superdiagonals.
N is INTEGER
The order of the matrix A.
DL is COMPLEX array, dimension (N-1)
On entry, DL must contain the (n-1) sub-diagonal elements of
On exit, DL is overwritten by the (n-1) multipliers that
define the matrix L from the LU factorization of A.
D is COMPLEX array, dimension (N)
On entry, D must contain the diagonal elements of A.
On exit, D is overwritten by the n diagonal elements of the
upper triangular matrix U from the LU factorization of A.
DU is COMPLEX array, dimension (N-1)
On entry, DU must contain the (n-1) super-diagonal elements
On exit, DU is overwritten by the (n-1) elements of the first
super-diagonal of U.
DU2 is COMPLEX array, dimension (N-2)
On exit, DU2 is overwritten by the (n-2) elements of the
second super-diagonal of U.
IPIV is INTEGER array, dimension (N)
The pivot indices; for 1 <= i <= n, row i of the matrix was
interchanged with row IPIV(i). IPIV(i) will always be either
i or i+1; IPIV(i) = i indicates a row interchange was not
INFO is INTEGER
= 0: successful exit
< 0: if INFO = -k, the k-th argument had an illegal value
> 0: if INFO = k, U(k,k) is exactly zero. The factorization
has been completed, but the factor U is exactly
singular, and division by zero will occur if it is used
to solve a system of equations.
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
Definition at line 125 of file cgttrf.f.
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 cgttrf.f(3)