scaling for polyfit.m [patch]

[John W. Eaton]

On  9-Aug-2006, Thomas Weber wrote:

| some time ago we had a bug[1] filed in Debian against polyfit.m; it
| breaks down for large values of x (which is known and a problem in
| Matlab as well). 
| 
| Based on the idea of the bug reporter, I've changed the polyfit function
| to always apply scaling, making it work for large x values.
| 
| The patch is attached; it includes a test with the data provided in the
| bugreport. 
| 
| One thing where I was unsure is which polynomial to use for calculating
| the values of S; I've taken the scaled polynomial because I think most
| people want the conditition value for the actual calculation.


I'm not sure that we should always do the scaling.  Maybe it should be
optional?

jwe