ztrcon.f File Reference

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Functions/Subroutines
subroutine	ztrcon (NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, RWORK, INFO)
	ZTRCON

---

Function/Subroutine Documentation

subroutine ztrcon	(	character	NORM,
		character	UPLO,
		character	DIAG,
		integer	N,
		complex*16, dimension( lda, * )	A,
		integer	LDA,
		double precision	RCOND,
		complex*16, dimension( * )	WORK,
		double precision, dimension( * )	RWORK,
		integer	INFO
	)

ZTRCON

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Purpose:

 ZTRCON 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)) ).

Parameters:

[in]	NORM	NORM is 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.
[in]	UPLO	UPLO is CHARACTER*1 = 'U': A is upper triangular; = 'L': A is lower triangular.
[in]	DIAG	DIAG is CHARACTER*1 = 'N': A is non-unit triangular; = 'U': A is unit triangular.
[in]	N	N is INTEGER The order of the matrix A. N >= 0.
[in]	A	A is COMPLEX*16 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 = 'U', the diagonal elements of A are also not referenced and are assumed to be 1.
[in]	LDA	LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).
[out]	RCOND	RCOND is DOUBLE PRECISION The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))).
[out]	WORK	WORK is COMPLEX*16 array, dimension (2*N)
[out]	RWORK	RWORK is DOUBLE PRECISION array, dimension (N)
[out]	INFO	INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 137 of file ztrcon.f.

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