zhpco

NAME

zhpco - (obsolete) compute the UDU factorization and condition number of a Hermitian matrix A in packed storage. If the condition number is not needed then xHPFA is slightly faster. It is typical to follow a call to xHPCO with a call to xHPSL to solve Ax = b or to xHPDI to compute the determinant, inverse, and inertia of A.

SYNOPSIS

  SUBROUTINE ZHPCO( A, N, IPIVOT, RCOND, WORK)
  DOUBLE COMPLEX A(*), WORK(*)
  INTEGER N
  INTEGER IPIVOT(*)
  DOUBLE PRECISION RCOND
 
  SUBROUTINE ZHPCO_64( A, N, IPIVOT, RCOND, WORK)
  DOUBLE COMPLEX A(*), WORK(*)
  INTEGER*8 N
  INTEGER*8 IPIVOT(*)
  DOUBLE PRECISION RCOND

C INTERFACE

#include <sunperf.h>

void zhpco(doublecomplex *a, int n, int *ipivot, double *rcond);

void zhpco_64(doublecomplex *a, long n, long *ipivot, double *rcond);

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.
* RCOND (output): On exit, an estimate of the reciprocal condition number of A. 0.0 <= RCOND <= 1.0. As the value of RCOND gets smaller, operations with A such as solving Ax = b may become less stable. If RCOND satisfies RCOND + 1.0 = 1.0 then A may be singular to working precision.
* WORK (workspace): Scratch array with a dimension of N.