CPTTRF(3)      LAPACK routine of NEC Numeric Library Collection      CPTTRF(3)



NAME
       CPTTRF

SYNOPSIS
       SUBROUTINE CPTTRF (N, D, E, INFO)



PURPOSE
            CPTTRF 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.




ARGUMENTS
           N         (input)
                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           D         (input/output)
                     D is REAL 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         (input/output)
                     E is COMPLEX 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      (output)
                     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.



LAPACK routine                  31 October 2017                      CPTTRF(3)