NAME

SYNOPSIS

  SUBROUTINE ZPBTRF( UPLO, N, NDIAG, A, LDA, INFO)
  CHARACTER * 1 UPLO
  DOUBLE COMPLEX A(LDA,*)
  INTEGER N, NDIAG, LDA, INFO
 
  SUBROUTINE ZPBTRF_64( UPLO, N, NDIAG, A, LDA, INFO)
  CHARACTER * 1 UPLO
  DOUBLE COMPLEX A(LDA,*)
  INTEGER*8 N, NDIAG, LDA, INFO
 

F95 INTERFACE

  SUBROUTINE PBTRF( UPLO, [N], NDIAG, A, [LDA], [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX(8), DIMENSION(:,:) :: A
  INTEGER :: N, NDIAG, LDA, INFO
 
  SUBROUTINE PBTRF_64( UPLO, [N], NDIAG, A, [LDA], [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX(8), DIMENSION(:,:) :: A
  INTEGER(8) :: N, NDIAG, LDA, INFO
 

C INTERFACE

void zpbtrf(char uplo, int n, int ndiag, doublecomplex *a, int lda, int *info);

void zpbtrf_64(char uplo, long n, long ndiag, doublecomplex *a, long lda, 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.

* NDIAG (input)

The number of superdiagonals of the matrix A if UPLO = 'U', or the number of subdiagonals if UPLO = 'L'. NDIAG >= 0.

* A (input/output)

On entry, the upper or lower triangle of the Hermitian band matrix A, stored in the first NDIAG+1 rows of the array. The j-th column of A is stored in the j-th column of the array A as follows: if UPLO = 'U', A(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j; if UPLO = 'L', A(1+i-j,j) = A(i,j) for j<=i<=min(n,j+kd).

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

* LDA (input)

The leading dimension of the array A. LDA >= NDIAG+1.

* INFO (output)