NAME

SYNOPSIS

  SUBROUTINE SPBSV( UPLO, N, NDIAG, NRHS, A, LDA, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER N, NDIAG, NRHS, LDA, LDB, INFO
  REAL A(LDA,*), B(LDB,*)
 
  SUBROUTINE SPBSV_64( UPLO, N, NDIAG, NRHS, A, LDA, B, LDB, INFO)
  CHARACTER * 1 UPLO
  INTEGER*8 N, NDIAG, NRHS, LDA, LDB, INFO
  REAL A(LDA,*), B(LDB,*)
 

F95 INTERFACE

  SUBROUTINE PBSV( UPLO, [N], NDIAG, [NRHS], A, [LDA], B, [LDB], [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER :: N, NDIAG, NRHS, LDA, LDB, INFO
  REAL, DIMENSION(:,:) :: A, B
 
  SUBROUTINE PBSV_64( UPLO, [N], NDIAG, [NRHS], A, [LDA], B, [LDB], 
 *       [INFO])
  CHARACTER(LEN=1) :: UPLO
  INTEGER(8) :: N, NDIAG, NRHS, LDA, LDB, INFO
  REAL, DIMENSION(:,:) :: A, B
 

C INTERFACE

void spbsv(char uplo, int n, int ndiag, int nrhs, float *a, int lda, float *b, int ldb, int *info);

void spbsv_64(char uplo, long n, long ndiag, long nrhs, float *a, long lda, float *b, long ldb, long *info);

PURPOSE

The Cholesky decomposition is used to factor A as

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

where U is an upper triangular band matrix, and L is a lower triangular band matrix, with the same number of superdiagonals or subdiagonals as A. The factored form of A is then used to solve the system of equations A * X = B.

ARGUMENTS

* UPLO (input)

* N (input)

The number of linear equations, i.e., 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.

* NRHS (input)

The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.

* A (input/output)

On entry, the upper or lower triangle of the symmetric 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(NDIAG+1+i-j,j) = A(i,j) for max(1,j-NDIAG)<=i<=j; if UPLO = 'L', A(1+i-j,j) = A(i,j) for j<=i<=min(N,j+NDIAG). See below for further details.

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

* LDA (input)

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

* B (input/output)

On entry, the N-by-NRHS right hand side matrix B. On exit, if INFO = 0, the N-by-NRHS solution matrix X.

* LDB (input)

The leading dimension of the array B. LDB >= max(1,N).

* INFO (output)