dtpcon man page on IRIX

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DTPCON(3F)							    DTPCON(3F)

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 number 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.

									Page 1

DTPCON(3F)							    DTPCON(3F)

     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

									Page 2

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