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Old 11-19-2006, 05:16 PM   #1
Mgellis
 
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Default Rounding questions...official ruling?

Okay, I apologize if these are stupid questions, or if I'm just missing the passage that clarifies things, but the rules are not entirely clear on this point...

1) In the Basic Set, it says one should round fractional point costs up on advantages. That certainly makes sense if you're rounding 3.75 points to 4 or 17.5 points to 18, but what about something like 40.2 points? Should that be rounded up to 41 points or, because it is below the .5 mark, down to 40 points?

2) In GURPS Traveller: Interstellar Wars, the formula for calculating the number of turrets one can have on a ship of a certain size directs one to "round down to the nearest integer." Obviously, if the number one has to round is 1.5, it makes sense that one should round down to 1, but what about 1.98? Should it be rounded down to 1 or to the nearest integer...2? (The example in the book does the latter, which I think makes more sense, but the rule itself as written is not entirely clear.)

Thanks.

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Old 11-19-2006, 05:33 PM   #2
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Default Re: Rounding questions...official ruling?

Quote:
Originally Posted by Mgellis
Okay, I apologize if these are stupid questions, or if I'm just missing the passage that clarifies things, but the rules are not entirely clear on this point...

1) In the Basic Set, it says one should round fractional point costs up on advantages. That certainly makes sense if you're rounding 3.75 points to 4 or 17.5 points to 18, but what about something like 40.2 points? Should that be rounded up to 41 points or, because it is below the .5 mark, down to 40 points?
Officially it's always round up - not round naturally, or scientifically. Just flat up. The rules are actually pretty clear on this.

Quote:
Originally Posted by Mgellis
2) In GURPS Traveller: Interstellar Wars, the formula for calculating the number of turrets one can have on a ship of a certain size directs one to "round down to the nearest integer." Obviously, if the number one has to round is 1.5, it makes sense that one should round down to 1, but what about 1.98? Should it be rounded down to 1 or to the nearest integer...2? (The example in the book does the latter, which I think makes more sense, but the rule itself as written is not entirely clear.)
I don't have ISW but the rule sounds pretty clear. Round down to the nearest integer: ie chop off all the decimal places. What ISN'T clear is why the example isn't following the rule :D
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Old 11-19-2006, 07:12 PM   #3
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Default Re: Rounding questions...official ruling?

I realize this doesn't help with planets and such, but ISTR it's always to the disadvantage of the PC.
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Old 11-20-2006, 01:35 AM   #4
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Default Re: Rounding questions...official ruling?

I don't see how either of these rules are at all unclear. "Round down to the nearest integer" is completely unambiguous

4.5 becomes 4.

125.8 becomes 125.

8.999456 becomes 8.

If the rules wanted there to be an exception, they'd state it.

So yes, if your character buys a modified advantage which ends up costing 70.05 character points, you round up to 71.
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Old 11-20-2006, 05:53 AM   #5
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Default Re: Rounding questions...official ruling?

I agree, and I have no trouble with the character point question; for that one, I just wanted to be sure I was getting it right.

The ship design question is a little harder--the rule, as written, makes sense, but the example in the book (a 100-dton needle patrol craft) SHOULD have 1 turret (1.98, rounded down to 1) but it is listed as having 2. That's why I'm asking...did they mean "round to the nearest integer, rounding down if the decimal is .5" or was it just a mistake?

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Old 11-20-2006, 10:05 AM   #6
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Default Re: Rounding questions...official ruling?

* Fractional character points always round up; 20.99, 20.9, 20.5, 20.1, 20.01, 20.001 . . . all become 21.

* Everything else is meant to be taken literally, regardless of whether the author forgot his own rounding conventions and/or an editor helpfully (but wrongly) rounded in another, more traditional way.

As an editor, I personally change all rules phrased like "round down to the next-lowest whole number" to "drop all fractions," because most people find it more intuitive to use.
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Old 11-22-2006, 12:20 PM   #7
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Default Re: Rounding questions...official ruling?

What about multiple possible roundings? Are there any offical rulings for them?


Do 4 levels of an advantage costing 5.2 points each level cost 21 (5.2*4 then round up) or (5.2 rounded up to 6 times 4 is 24)?

Does someone with a base speed 6.75, no modifiers for Move, in Medium Encumberance move at 4 (6.75*.6 = 4.05 then round down) or 3 (6*.6 = 3.6 then round down)?

Does 4 levels of Reduced Time on Shapeshifting let you change in 1 second (10, 5, 3, 2, 1) or as a free action (10, 5, 2.5, 1.25, .625)?
Or another way to put it, would a power with a base time of 1 minute need 8 levels of Recuced Time for a free action (60, 30, 15, 8, 4, 2, 1, 0), 7 (60, 30, 7.5, 3.75, 1.875, .9375 so 1, then 1 more to make it free), or 6 (60, 30, 7.5, 3.75, 1.875, .9375)?
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Old 11-22-2006, 03:07 PM   #8
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Default Re: Rounding questions...official ruling?

Quote:
Originally Posted by sgt.sargent

Do 4 levels of an advantage costing 5.2 points each level cost 21 (5.2*4 then round up) or (5.2 rounded up to 6 times 4 is 24)?
Advantages aren't likely to cost 5.2 points a level, because virtually all of them have whole-numbered costs. You might be thinking of enhancements and modifiers . . . which are always applied to final cost after buying N levels, and never, ever, for any reason applied to per-level costs. Should an advantage actually yield a fraction before modifiers, you're meant to round the fraction up and then apply the modifiers and round that result up.

Quote:
Originally Posted by sgt.sargent

Does someone with a base speed 6.75, no modifiers for Move, in Medium Encumberance move at 4 (6.75*.6 = 4.05 then round down) or 3 (6*.6 = 3.6 then round down)?
Basic Move is always a whole-numbered quantity figured by dropping the fraction from Basic Speed. Modifiers to Move apply to Basic Move, not to Basic Speed. So in your example, Basic Speed 6.75 means Basic Move 6, which then gives Move 3.

Quote:
Originally Posted by sgt.sargent

Does 4 levels of Reduced Time on Shapeshifting let you change in 1 second (10, 5, 3, 2, 1) or as a free action (10, 5, 2.5, 1.25, .625)?
Or another way to put it, would a power with a base time of 1 minute need 8 levels of Recuced Time for a free action (60, 30, 15, 8, 4, 2, 1, 0), 7 (60, 30, 7.5, 3.75, 1.875, .9375 so 1, then 1 more to make it free), or 6 (60, 30, 7.5, 3.75, 1.875, .9375)?
Halve and round up at each level; 10, 5, 3, 2, 1, 0 is correct; so is 60, 30, 15, 8, 4, 2, 1, 0.
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Old 11-22-2006, 03:19 PM   #9
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Default Re: Rounding questions...official ruling?

Quote:
Originally Posted by sgt.sargent
What about multiple possible roundings? Are there any offical rulings for them?
Slightly different in each case, but here goes.
Quote:
Do 4 levels of an advantage costing 5.2 points each level cost 21 (5.2*4 then round up) or (5.2 rounded up to 6 times 4 is 24)?
Leveled advantages are reduced based on the total cost, so your first answer here.
Quote:
Does someone with a base speed 6.75, no modifiers for Move, in Medium Encumberance move at 4 (6.75*.6 = 4.05 then round down) or 3 (6*.6 = 3.6 then round down)?
Encumbrance always reduces your move and isn't calculated at all on your base speed, so the answer here is 3.
Quote:
Does 4 levels of Reduced Time on Shapeshifting let you change in 1 second (10, 5, 3, 2, 1) or as a free action (10, 5, 2.5, 1.25, .625)?
Or another way to put it, would a power with a base time of 1 minute need 8 levels of Recuced Time for a free action (60, 30, 15, 8, 4, 2, 1, 0), 7 (60, 30, 7.5, 3.75, 1.875, .9375 so 1, then 1 more to make it free), or 6 (60, 30, 7.5, 3.75, 1.875, .9375)?
The first of each of your examples is Kromm's canonical answer, although the second seems an equally reasonable alternative.
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