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zgttrf.f(3) LAPACK zgttrf.f(3)

zgttrf.f -


subroutine zgttrf (N, DL, D, DU, DU2, IPIV, INFO)
 
ZGTTRF

ZGTTRF
Purpose:
 ZGTTRF 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.
Parameters:
N
          N is INTEGER
          The order of the matrix A.
DL
          DL is COMPLEX*16 array, dimension (N-1)
          On entry, DL must contain the (n-1) sub-diagonal elements of
          A.
On exit, DL is overwritten by the (n-1) multipliers that define the matrix L from the LU factorization of A.
D
          D is COMPLEX*16 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
          DU is COMPLEX*16 array, dimension (N-1)
          On entry, DU must contain the (n-1) super-diagonal elements
          of A.
On exit, DU is overwritten by the (n-1) elements of the first super-diagonal of U.
DU2
          DU2 is COMPLEX*16 array, dimension (N-2)
          On exit, DU2 is overwritten by the (n-2) elements of the
          second super-diagonal of U.
IPIV
          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
          required.
INFO
          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.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 125 of file zgttrf.f.

Generated automatically by Doxygen for LAPACK from the source code.
Sat Nov 16 2013 Version 3.4.2

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