## RCOND Reciprocal Condition Number Estimate

Section: Array Generation and Manipulations

### Usage

The`rcond`

function is a FreeMat wrapper around LAPACKs
function `XGECON`

, which estimates the 1-norm condition
number (reciprocal). For the details of the algorithm see
the LAPACK documentation. The syntax for its use is
x = rcond(A)

where `A`

is a matrix.

### Example

Here is the reciprocal condition number for a random square matrix--> A = rand(30); --> rcond(A) ans = 3.5040e-04

And here we calculate the same value using the definition of (reciprocal) condition number

--> 1/(norm(A,1)*norm(inv(A),1)) ans = 3.5040e-04

Note that the values are very similar. LAPACKs `rcond`

function is far more efficient than the explicit calculation
(which is also used by the `cond`

function.