Hussein,

>I used to krig with the IDW or the Spline in Arc/View,

Kriging is a separate process from IDW or Spline.  Check the help file
under interpolation (I think that's where the help files for the three
interpolation routines are).  Marco Boeringa has written scripts/extension
that make full use of all features of the kriging algorithms provided in
Spatial Analyst.  Those are available from teh ESRI website.

>Cokriging software externally i.e. outside the GIS environment.

Then it sounds that what you really need to do is write an interface
between the two programs to allow you to export the data out of AV to the
external package, and then reimport the result.  I confess this is beyond
my experience, but should be possible even if it needs to  be run in steps,
instead of seamlessly.

Regards,

Matthew

Matthew L. Adams
CSIRO Land and Water
Private Bag, P.O.
Wembley, WA 6014
Tel: 08-93336381
Fax: 08-93336121
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