Excellent! Thanks,

I'd dismissed MMULT as useless earlier because of its limits on
multiplying matrices bigger than 51 or whatever it is.
I didn't think to use it as an alternative way to calculate the
dotproduct.

Thanks again.

Dave Peterson wrote in message ...
That actually returns an array: ={999} (if you hit F2|F9 to see the result)

This will return a simple value:
=INDEX(MMULT(Normalised!$A1:$W1,pcomps!A$2:A$24),1 ,1)