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RedHat 9 (Linux i386) - man page for dtpcon (redhat section l)

DTPCON(l)					)					DTPCON(l)

NAME
       DTPCON  - estimate the reciprocal of the condition number of a packed triangular matrix A,
       in either the 1-norm or the infinity-norm

SYNOPSIS
       SUBROUTINE DTPCON( NORM, UPLO, DIAG, N, AP, RCOND, WORK, IWORK, INFO )

	   CHARACTER	  DIAG, NORM, UPLO

	   INTEGER	  INFO, N

	   DOUBLE	  PRECISION RCOND

	   INTEGER	  IWORK( * )

	   DOUBLE	  PRECISION AP( * ), WORK( * )

PURPOSE
       DTPCON estimates the reciprocal of the condition number of a packed triangular  matrix  A,
       in  either  the 1-norm or the infinity-norm.  The norm of A is computed and an estimate is
       obtained for norm(inv(A)), then the reciprocal of the condition number is computed as
	  RCOND = 1 / ( norm(A) * norm(inv(A)) ).

ARGUMENTS
       NORM    (input) CHARACTER*1
	       Specifies whether the 1-norm condition number or the infinity-norm condition  num-
	       ber is required:
	       = '1' or 'O':  1-norm;
	       = 'I':	      Infinity-norm.

       UPLO    (input) CHARACTER*1
	       = 'U':  A is upper triangular;
	       = 'L':  A is lower triangular.

       DIAG    (input) CHARACTER*1
	       = 'N':  A is non-unit triangular;
	       = 'U':  A is unit triangular.

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

       AP      (input) DOUBLE PRECISION array, dimension (N*(N+1)/2)
	       The  upper or lower triangular matrix A, packed columnwise in a linear array.  The
	       j-th column of A is stored in the array AP as follows:  if  UPLO  =  'U',  AP(i	+
	       (j-1)*j/2)  =  A(i,j)  for 1<=i<=j; if UPLO = 'L', AP(i + (j-1)*(2n-j)/2) = A(i,j)
	       for j<=i<=n.  If DIAG = 'U', the diagonal elements of A are not referenced and are
	       assumed to be 1.

       RCOND   (output) DOUBLE PRECISION
	       The  reciprocal	of  the  condition  number  of	the matrix A, computed as RCOND =
	       1/(norm(A) * norm(inv(A))).

       WORK    (workspace) DOUBLE PRECISION array, dimension (3*N)

       IWORK   (workspace) INTEGER array, dimension (N)

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

LAPACK version 3.0			   15 June 2000 				DTPCON(l)


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