LAPACK
3.6.1
LAPACK: Linear Algebra PACKage
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subroutine zgttrf | ( | integer | N, |
complex*16, dimension( * ) | DL, | ||
complex*16, dimension( * ) | D, | ||
complex*16, dimension( * ) | DU, | ||
complex*16, dimension( * ) | DU2, | ||
integer, dimension( * ) | IPIV, | ||
integer | INFO | ||
) |
ZGTTRF
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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.
[in] | N | N is INTEGER The order of the matrix A. |
[in,out] | 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. |
[in,out] | 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. |
[in,out] | 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. |
[out] | 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. |
[out] | 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. |
[out] | 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. |
Definition at line 126 of file zgttrf.f.