I am trying to a UDF that uses arrays and worksheet matrix functions to
calculate the intersection of three spheres. I have declared several 1- and
2-D double arrays to store data.

I originally declared these array variables as doubles, but I found I could
not use functions like the following example:

Dim tempMatrix(1 to 3, 1 to 3) as Double
tempVector = identity(tempVector)

where "identity" is a UDF that accepts a square array and sets it to an
identity matrix. I imagine that I cannot assign the function's return to
tempVector because it is a double array, not a Variant (i.e. not an object).

I declared these variables as Doubles because I have read that variants are
slow and inefficient and should be avoided if possible. How then would be
the best way to fill these variable? Should I use subroutines and send the
double array as a parameter? Or should I use variant arrays?

But then, variant arrays cannot be initialized with dimensions, right? I.e:

Dim tempVector(1 to 3, 1 to 3) as Variant

I'm looking for the Best Practice here. Thanks.
Pflugs