rcond: How do I use it?

[John W. Eaton]

On 13-Mar-1999, Gary Church <address@hidden> wrote:

| I'm running the most recent stable release of Octave for OS/2. I want to
| use the "rcond" function to estimate the goodness of the inverse of a
| matrix but it doesn't seem to be available to me.
| 
| In one of my programs where I'm calculating the inverse of a large
| Vandermond matrix, I get the following warning:
| 
| warning: inverse: matrix singular to machine precision, rcond =
| 8.67916e-307
| 
| How do I calculate the rcond value directly?

The value of `rcond' in the error message is just an estimate of the
inverse of the condition number of the matrix.  You can use `cond' to
compute the condition number, so 1/cond(x) should give you something
close to rcond(x).

jwe