zpbcon zpbtrf zpbtrs zptcon zpttrf zpttrs

zpttrf() void zpttrf ( int  n, double  d[], doublecomplex  e[], int *  info  ) LDLH factorization of a Hermitian positive definite tridiagonal matrix Purpose This routine computes the L*D*L^H factorization of a Hermitian positive definite tridiagonal matrix A. The factorization may also be regarded as having the form A = U^H*D*U. Parameters [in] n Order of the matrix A. (n >= 0) (If n = 0, returns without computation) [in,out] d[] Array d[ld] (ld >= n) [in] n diagonal elements of the Hermitian positive definite tridiagonal matrix A. [out] n diagonal elements of the diagonal matrix D from the L*D*L^H factorization of A. [in,out] e[] Array e[le] (le >= n - 1) [in] n-1 sub-diagonal elements of the Hermitian positive definite tridiagonal matrix A. [out] n-1 sub-diagonal elements of the unit bidiagonal factor L from the L*D*L^H factorization of A. E can also be regarded as the super-diagonal of the unit bidiagonal factor U from the U^H*D*U factorization of A. [out] info = 0: Successful exit = -1: The argument n had an illegal value (n < 0) = i > 0: The leading minor of order i is not positive definite. If i < n, the factorization could not been completed, while if i = n, the factorization was completed, but d[n-1] <= 0. Reference LAPACK