That's a neat trick

[spiffturk]

Theory is nasty. Case in point, it just became useful to rewrite (ab + cd) as [(a+d)*(b+c) - ad - bc]. That's some counterintuitive bullshit, right there.

Comments

[one_word]

is addition that much faster to compute than multiplication?

I mean, you've gone from 2 multiplication steps and 1 addition to 1 multiplication and four addition....

Or is that completely off?

[spiffturk]

You're not far off, actually