# cpttrf.f man page

cpttrf.f

## Synopsis

### Functions/Subroutines

subroutine cpttrf (N, D, E, INFO)
CPTTRF

## Function/Subroutine Documentation

### subroutine cpttrf (integer N, real, dimension( * ) D, complex, dimension( * ) E, integer INFO)

CPTTRF

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.```
Parameters:

N

```          N is INTEGER
The order of the matrix A.  N >= 0.```

D

```          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

```          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

```          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.```
Author:

Univ. of Tennessee

Univ. of California Berkeley

NAG Ltd.

Date:

December 2016

Definition at line 94 of file cpttrf.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page cpttrf(3) is an alias of cpttrf.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK