question about doing a regression

[Brent A McDaniel <gte328r@xxxxxxxxxxxxxxxxxxxxx>]

Hi Ferreters,

I'm trying to regress a timeseries onto an existing index and I'm having
some trouble doing it.  If someone could help me out I'd be greatly
appreciative.

Here's what I'm starting with:
I have a variable airhp which is defined on a grid 144x38x17x151 and an
index that is defined on a grid i=1:17, j=1:14610 where, for the index, is
the the level and j is the day.  What I want to do is, for a given level,
generate a regression map (144x38).  I want to do a standard regression,
multiplying the value of airhp at a given time step and location by the
index value at that time step and summing these all up.  The problem that
I'm having is that the indices don't match up (i for airhp doesn't
correspond to i for the index file).  Is what I'm trying possible in
ferret or do I need to write an external function to do it?

Thanks in advance,

Brent