Re: ErrorEstimate

• To: Jakob Svensson <pjds@xxxxxxxxxx>
• Subject: Re: ErrorEstimate
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Wed, 30 Jan 2002 11:54:50 -0600

Hi Jakob,

> I am trying to figure out how the ErrorEstimate classes work, but can't
> quite make it out from the developers guide, tutorial, javadoc or the
> archive. I can understand what happens for Reals and the range components of
> FlatFields, but what happens when the domain Set for a FlatField has an
> ErrorEstimate?

If you resample() a Field to a Set that has ErrorEstimates,
these contribute to the errors of the resampled Field values.
This hasn't been tested much.

> Also, I can see that Data.INDEPENDENT uses a linear 'error
> propagation' algorithm, but what does actually Data.DEPENDENT do (doesn't
> one need to know the functional form of the dependency?). Is there any
> auxiliary documentation somewhere, or references to the algorithms used?

For Data.DEPENDENT the system uses the worst case error
propagation, where they are simply added. This is essentially
interval arithmetic. For Data.INDEPENDENT the system uses
root mean square error propagation.

Sorry to say there isn't any detailed documentation, except
for a little bit in Tom's data model tutorial at:

  http://www.ssec.wisc.edu/~tomw/visadtutor/visaddata.html

Regards,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html

• References:
  • ErrorEstimate
    • From: Jakob Svensson