dspfa

NAME

dspfa - (obsolete) compute the UDU factorization of a symmetric matrix A in packed storage. It is typical to follow a call to SSPFA with a call to SSPSL to solve Ax = b or to SSPDI to compute the determinant, inverse, and inertia of A.

SYNOPSIS 

  SUBROUTINE DSPFA( A, N, IPIVOT, INFO)
  INTEGER N, INFO
  INTEGER IPIVOT(*)
  DOUBLE PRECISION A(*)
 
  SUBROUTINE DSPFA_64( A, N, IPIVOT, INFO)
  INTEGER*8 N, INFO
  INTEGER*8 IPIVOT(*)
  DOUBLE PRECISION A(*)

C INTERFACE

#include <sunperf.h>

void dspfa(double *a, int n, int *ipivot, int *info);

void dspfa_64(double *a, long n, long *ipivot, long *info);

ARGUMENTS

* A (input/output)
On entry, the upper triangle of the matrix A. On exit, a UDU factorization of the matrix A.

* N (input)
Order of the matrix A. N >= 0.

* IPIVOT (output)
On exit, a vector of pivot indices.

* INFO (output)
On exit:

INFO = 0 Subroutine completed normally.

INFO > 0 Returns a value k if the kth pivot block is singular to indicate that SSPSL or SSPDI will divide by zero if called.