SRC/zpttrf.f(3) | Library Functions Manual | SRC/zpttrf.f(3) |
NAME
SRC/zpttrf.f
SYNOPSIS
Functions/Subroutines
subroutine zpttrf (n, d, e, info)
ZPTTRF
Function/Subroutine Documentation
subroutine zpttrf (integer n, double precision, dimension( * ) d, complex*16, dimension( * ) e, integer info)
ZPTTRF
Purpose:
ZPTTRF computes the L*D*L**H factorization of a complex Hermitian positive definite tridiagonal matrix A. The factorization may also be regarded as having the form A = U**H *D*U.
Parameters
N
N is INTEGER The order of the matrix A. N >= 0.
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**H factorization of A.
E
E is COMPLEX*16 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**H factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the U**H *D*U factorization of A.
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 principal minor of order k is not positive; if k < N, the factorization could not be completed, while if k = N, the factorization was completed, but D(N) <= 0.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 91 of file zpttrf.f.
Author
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