NAME

SYNOPSIS

  SUBROUTINE ZPPTRF( UPLO, N, A, INFO)
  CHARACTER * 1 UPLO
  DOUBLE COMPLEX A(*)
  INTEGER N, INFO
 
  SUBROUTINE ZPPTRF_64( UPLO, N, A, INFO)
  CHARACTER * 1 UPLO
  DOUBLE COMPLEX A(*)
  INTEGER*8 N, INFO
 

F95 INTERFACE

  SUBROUTINE PPTRF( UPLO, N, A, [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX(8), DIMENSION(:) :: A
  INTEGER :: N, INFO
 
  SUBROUTINE PPTRF_64( UPLO, N, A, [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX(8), DIMENSION(:) :: A
  INTEGER(8) :: N, INFO
 

C INTERFACE

void zpptrf(char uplo, int n, doublecomplex *a, int *info);

void zpptrf_64(char uplo, long n, doublecomplex *a, long *info);

PURPOSE

The factorization has the form

   A = U**H * U,  if UPLO = 'U', or
   A = L  * L**H,  if UPLO = 'L',

where U is an upper triangular matrix and L is lower triangular.

ARGUMENTS

* UPLO (input)

* N (input)

The order of the matrix A. N >= 0.

* A (input/output)

On entry, the upper or lower triangle of the Hermitian matrix A, packed columnwise in a linear array. The j-th column of A is stored in the array A as follows: if UPLO = 'U', A(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', A(i + (j-1)*(2n-j)/2) = A(i,j) for j<=i<=n. See below for further details.

On exit, if INFO = 0, the triangular factor U or L from the Cholesky factorization A = U**H*U or A = L*L**H, in the same storage format as A.

* INFO (output)