QUOTE (Udoshi @ Aug 30 2012, 04:31 PM)

I dunno, man, you're still doing addition before multiplication. If you're adding together the multipliers before multiplying them, you're breaking the order of operations.

The P in PEMDAS means you resolve the inside of a parenthesis to generate a value. That can and will result in addition being done before multiplication.

(4 + 3 * 9)^2 means you resolve the 4 + 3 * 9 first according to PEMDAS. Which means you do the 3 * 9 = 27 then add 4 then apply the square for 961. The top method that I wrote is the longhand for the additive method. You don't actually do any addition before multiplication with that method. The bottom one is the multiplicative method which has the addition before multiplication.

1 - (1 * 10 / 100) - (1 * 10 / 100) - (1 * 20 / 100) + (1 * 20 / 100)

1 - (10 / 100) - (10 / 100) - (20 / 200) + (20 / 100)

1 - (0.1) - (0.1) - (0.2) + (0.2)

1 - 0.1 - 0.1 - 0.2 + 0.2

0.9 - 0.1 - 0.2 + 0.2

0.8 - 0.2 + 0.2

0.6 + 0.2

0.8

1 * (1 - 10 / 100) * ( 1 - 10 / 100) * (1 - 20 / 100) * (1 + 20 / 100)

1 * (1 - 0.1) * (1 - 0.1) * (1 - 0.2) * (1 + 0.

1 * (0.9) * (0.9) * (0.

* (1.2)

1 * 0.9 * 0.9 * 0.8 * 1.2

0.9 * 0.9 * 0.8 * 1.2

0.81 * 0.8 * 1.2

0.648 * 1.2

0.7776

QUOTE (Udoshi @ Aug 30 2012, 04:31 PM)

If games want to have extra-fancy not-breaking-the-rules math they need to make that clear in the rule book. The Cancer Game's special rules for critical damage multipliers stacking up is a prime example of additive multiplication(a doubled double is a triple) instead of real multiplication.(it would be four times)

All in all, I feel that adding the discounts up first saves a ton of math hastle, though it is super dumb this wasn't clarified officially and set in stone near launch. For such a core mechanic, so many years after launch, its wonderful that people still can't figure out how to calculate things right.

The additive method I believe is call summing the percentages or something like that. 50% of base + 50% of base + 50% of base. This is an entirely legitimate method of doing things.

It fairly easy to see how it was included in the original SR4 book. There were only two things that affected essence cost and that was 'ware grade and the Sensitive System negative quality, but it says to double the loss so it probably is supposed to be applied at the very end since it is a doubling and a not a 100% increase. The addition of biocompatibility, adaptsin, and secondhand 'ware is where it was broken since that is where stacking of essence cost modifiers should have been addressed.