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 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**

`rcond`

uses LAPACK routines to compute the estimate of the reciprocal condition number:

Matrix |
Routine |

Real |
`DLANGE` , `DGETRF` , `DGECON` |

Complex |
`ZLANGE` , `ZGETRF` , `ZGECON` |

**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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