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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine dpttrf | ( | integer | N, |
double precision, dimension( * ) | D, | ||
double precision, dimension( * ) | E, | ||
integer | INFO | ||
) |
DPTTRF
Download DPTTRF + dependencies [TGZ] [ZIP] [TXT]
DPTTRF computes the L*D*L**T factorization of a real symmetric positive definite tridiagonal matrix A. The factorization may also be regarded as having the form A = U**T*D*U.
[in] | N | N is INTEGER The order of the matrix A. N >= 0. |
[in,out] | D | D is 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*L**T factorization of A. |
[in,out] | E | E is 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*L**T factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the U**T*D*U factorization of A. |
[out] | INFO | INFO is 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. |
Definition at line 93 of file dpttrf.f.