MATLAB Function Reference 
Matrix reciprocal condition number estimate
Syntax
Description
c = rcond(A)
returns an estimate for the reciprocal of the condition of A
in 1norm 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.
rbbox  real 
© 19942005 The MathWorks, Inc.