spbfa

NAME

spbfa - (obsolete) compute a Cholesky factorization of a symmetric positive definite matrix A in banded storage. It is typical to follow a call to SPBFA with a call to SPBSL to solve Ax = b or to SPBDI to compute the determinant of A.

SYNOPSIS

  SUBROUTINE SPBFA( A, LDA, N, NDIAG, INFO)
  INTEGER LDA, N, NDIAG, INFO
  REAL A(LDA,*)
 
  SUBROUTINE SPBFA_64( A, LDA, N, NDIAG, INFO)
  INTEGER*8 LDA, N, NDIAG, INFO
  REAL A(LDA,*)

C INTERFACE

#include <sunperf.h>

void spbfa(float *a, int lda, int n, int ndiag, int *info);

void spbfa_64(float *a, long lda, long n, long ndiag, long *info);

ARGUMENTS

* A (input/output)

On entry, the upper triangle of the matrix A. On exit, a Cholesky factorization of the matrix A.

* LDA (input)

Leading dimension of the array A as specified in a dimension or type statement. LDA >= NDIAG + 1.

* N (input)

Order of the matrix A. N >= 0.

* NDIAG (input)

Number of diagonals. N-1 >= NDIAG >= 0 but if N = 0 then NDIAG = 0.

* INFO (output)

On exit:

INFO = 0 Subroutine completed normally.

INFO > 0 Returns a value of k if the leading minor of order k is not positive definite.