ZSPCON(l)		LAPACK routine (version	1.1)		    ZSPCON(l)

NAME
  ZSPCON - estimate the	reciprocal of the condition number (in the 1-norm) of
  a complex symmetric packed matrix A using the	factorization A	= U*D*U**T or
  A = L*D*L**T computed	by ZSPTRF

SYNOPSIS

  SUBROUTINE ZSPCON( UPLO, N, AP, IPIV,	ANORM, RCOND, WORK, INFO )

      CHARACTER	     UPLO

      INTEGER	     INFO, N

      DOUBLE	     PRECISION ANORM, RCOND

      INTEGER	     IPIV( * )

      COMPLEX*16     AP( * ), WORK( * )

PURPOSE
  ZSPCON estimates the reciprocal of the condition number (in the 1-norm) of
  a complex symmetric packed matrix A using the	factorization A	= U*D*U**T or
  A = L*D*L**T computed	by ZSPTRF.

  An estimate is obtained for norm(inv(A)), and	the reciprocal of the condi-
  tion number is computed as RCOND = 1 / (ANORM	* norm(inv(A))).

ARGUMENTS

  UPLO	  (input) CHARACTER*1
	  Specifies whether the	details	of the factorization are stored	as an
	  upper	or lower triangular matrix.  = 'U':  Upper triangular, form
	  is A = U*D*U**T;
	  = 'L':  Lower	triangular, form is A =	L*D*L**T.

  N	  (input) INTEGER
	  The order of the matrix A.  N	>= 0.

  AP	  (input) COMPLEX*16 array, dimension (N*(N+1)/2)
	  The block diagonal matrix D and the multipliers used to obtain the
	  factor U or L	as computed by ZSPTRF, stored as a packed triangular
	  matrix.

  IPIV	  (input) INTEGER array, dimension (N)
	  Details of the interchanges and the block structure of D as deter-
	  mined	by ZSPTRF.

  ANORM	  (input) DOUBLE PRECISION
	  The 1-norm of	the original matrix A.

  RCOND	  (output) DOUBLE PRECISION
	  The reciprocal of the	condition number of the	matrix A, computed as
	  RCOND	= 1/(ANORM * AINVNM), where AINVNM is an estimate of the 1-
	  norm of inv(A) computed in this routine.

  WORK	  (workspace) COMPLEX*16 array,	dimension (2*N)

  INFO	  (output) INTEGER
	  = 0:	successful exit
	  < 0:	if INFO	= -i, the i-th argument	had an illegal value


Back to the listing of computational routines for linear equations