CTRCON man page on IRIX

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CTRCON(3F)							    CTRCON(3F)

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

SYNOPSIS
     SUBROUTINE CTRCON( NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, RWORK, INFO
			)

	 CHARACTER	DIAG, NORM, UPLO

	 INTEGER	INFO, LDA, N

	 REAL		RCOND

	 REAL		RWORK( * )

	 COMPLEX	A( LDA, * ), WORK( * )

PURPOSE
     CTRCON estimates the reciprocal of the condition number of a 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.

     A	     (input) COMPLEX array, dimension (LDA,N)
	     The triangular matrix A.  If UPLO = 'U', the leading N-by-N upper
	     triangular part of the array A contains the upper triangular
	     matrix, and the strictly lower triangular part of A is not
	     referenced.  If UPLO = 'L', the leading N-by-N lower triangular
	     part of the array A contains the lower triangular matrix, and the
	     strictly upper triangular part of A is not referenced.  If DIAG =

									Page 1

CTRCON(3F)							    CTRCON(3F)

	     'U', the diagonal elements of A are also not referenced and are
	     assumed to be 1.

     LDA     (input) INTEGER
	     The leading dimension of the array A.  LDA >= max(1,N).

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

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

     RWORK   (workspace) REAL 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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