NAME

SYNOPSIS

  SUBROUTINE SPOTRF( UPLO, N, A, LDA, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, LDA, INFO
  REAL A(LDA,*)
 
  SUBROUTINE SPOTRF_64( UPLO, N, A, LDA, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, LDA, INFO
  REAL A(LDA,*)
 

F95 INTERFACE

  SUBROUTINE POTRF( UPLO, [N], A, [LDA], [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER :: N, LDA, INFO
  REAL, DIMENSION(:,:) :: A
 
  SUBROUTINE POTRF_64( UPLO, [N], A, [LDA], [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER(8) :: N, LDA, INFO
  REAL, DIMENSION(:,:) :: A
 

C INTERFACE

void spotrf(char uplo, int n, float *a, int lda, int *info);

void spotrf_64(char uplo, long n, float *a, long lda, long *info);

PURPOSE

The factorization has the form

   A = U**T * U,  if UPLO = 'U', or
   A = L  * L**T,  if UPLO = 'L',

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

This is the block 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 symmetric 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, if INFO = 0, the factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T.

* LDA (input)

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

* INFO (output)