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Han · (This post was last modified: 12-12-2014 10:08 PM by Han.)

(12-12-2014 09:18 PM)Nigel (UK) Wrote: How about

Code:

sum_list(|a|) * sum_list(|b|)
where I've typed sum_list because I don't know how to type sigma? Or have I missed something?

Nigel (UK)

sum(abs(a))*sum(abs(b)) will do what you proposed. The multiplication described seems like a simple distribution (unless I misread the original post)
\[
(a_1 + a_2 + a_3 + \dotsm + a_n) ( b_1 + b_2 + b_3 + \dotsm + b_m )
=\]
\[ a_1 \cdot ( b_1 + b_2 + b_3 + \dotsm + b_m ) + a_1 \cdot
( b_1 + b_2 + b_3 + \dotsm + b_m ) + \dotsm
+ a_n \cdot ( b_1 + b_2 + b_3 + \dotsm + b_m ) \]
but with absolute values of each term.