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rcond - Matrix reciprocal condition number estimate

Syntax

c = rcond(A)

Description

c = rcond(A) returns an estimate for the reciprocal of the condition of A in 1-norm using the LAPACK condition estimator. If A is well conditioned, rcond(A) is near 1.0. If A is badly conditioned, rcond(A) is near 0.0. Compared to cond, rcond is a more efficient, but less reliable, method of estimating the condition of a matrix.

Algorithm

For full matrices A, rcond uses the LAPACK routines listed in the following table to compute the estimate of the reciprocal condition number.

	Real	Complex
A double	DLANGE, DGETRF, DGECON	ZLANGE, ZGETRF, ZGECON
A single	SLANGE, SGETRF, SGECON	CLANGE, CGETRF, CGECON

See Also

cond, condest, norm, normest, rank, svd

References

[1] Anderson, E., Z. Bai, C. Bischof, S. Blackford, J. Demmel, J. Dongarra, J.Du Croz, A. Greenbaum, S. Hammarling, A. McKenney, and D. Sorensen, LAPACK User's Guide (http://www.netlib.org/lapack/lug/lapack_lug.html), Third Edition, SIAM, Philadelphia, 1999.

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