NAME

SYNOPSIS

  SUBROUTINE CHETRF( UPLO, N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
  CHARACTER * 1 UPLO
  COMPLEX A(LDA,*), WORK(*)
  INTEGER N, LDA, LDWORK, INFO
  INTEGER IPIVOT(*)
 
  SUBROUTINE CHETRF_64( UPLO, N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
  CHARACTER * 1 UPLO
  COMPLEX A(LDA,*), WORK(*)
  INTEGER*8 N, LDA, LDWORK, INFO
  INTEGER*8 IPIVOT(*)
 

F95 INTERFACE

  SUBROUTINE HETRF( UPLO, [N], A, [LDA], IPIVOT, [WORK], [LDWORK], 
 *       [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX, DIMENSION(:) :: WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER :: N, LDA, LDWORK, INFO
  INTEGER, DIMENSION(:) :: IPIVOT
 
  SUBROUTINE HETRF_64( UPLO, [N], A, [LDA], IPIVOT, [WORK], [LDWORK], 
 *       [INFO])
  CHARACTER(LEN=1) :: UPLO
  COMPLEX, DIMENSION(:) :: WORK
  COMPLEX, DIMENSION(:,:) :: A
  INTEGER(8) :: N, LDA, LDWORK, INFO
  INTEGER(8), DIMENSION(:) :: IPIVOT
 

C INTERFACE

void chetrf(char uplo, int n, complex *a, int lda, int *ipivot, int *info);

void chetrf_64(char uplo, long n, complex *a, long lda, long *ipivot, long *info);

PURPOSE

   A = U*D*U**H  or  A = L*D*L**H

where U (or L) is a product of permutation and unit upper (lower) triangular matrices, and D is Hermitian and block diagonal with 1-by-1 and 2-by-2 diagonal blocks.

This is the blocked version of the algorithm, calling Level 3 BLAS.

ARGUMENTS

* UPLO (input)

* N (input)

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

* A (input/output)

On entry, the Hermitian matrix A. If UPLO = 'U', the leading N-by-N upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading N-by-N lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced.

On exit, the block diagonal matrix D and the multipliers used to obtain the factor U or L (see below for further details).

* LDA (input)

The leading dimension of the array A. LDA >= max(1,N).

* IPIVOT (output)

Details of the interchanges and the block structure of D. If IPIVOT(k) > 0, then rows and columns k and IPIVOT(k) were interchanged and D(k,k) is a 1-by-1 diagonal block. If UPLO = 'U' and IPIVOT(k) = IPIVOT(k-1) < 0, then rows and columns k-1 and -IPIVOT(k) were interchanged and D(k-1:k,k-1:k) is a 2-by-2 diagonal block. If UPLO = 'L' and IPIVOT(k) = IPIVOT(k+1) < 0, then rows and columns k+1 and -IPIVOT(k) were interchanged and D(k:k+1,k:k+1) is a 2-by-2 diagonal block.

* WORK (workspace)

On exit, if INFO = 0, WORK(1) returns the optimal LDWORK.

* LDWORK (input)

The length of WORK. LDWORK >=1. For best performance LDWORK >= N*NB, where NB is the block size returned by ILAENV.

* INFO (output)