18-05-2004 22:57									#31
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As has been stated before, optimally rushing units is not as simple as counting. For a perfect hurry cost, you must divide two numbers and calculate at least a few decimal places, then multiply that by another number. You can estimate the cost to within a few ECs fairly quickly, but the exact cost requires a little thinking.

Example: you have a former in construction that has 9 mineral accumulated towards a total cost of 20 minerals. This base is producing 3 minerals per turn. The minimal hurry cost would be:

28 ec to rush all the way
/ 11 minerals remaining
* 8 minerals desired
= (28 / 11) * 8, round up
= 2.545... * 8, round up
= 20.36..., round up
= 21

	18-05-2004 23:24									#32
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Ok, in that example I would have rushed for 22 ecs which equal to appr. 8.6 minerals. Will that 0.6 mineral become 1 mineral and be carried over to the next turn?

	19-05-2004 04:14									#33
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Nope, if you overpay, but not enough to buy one more mineral than you intended, the excess is lost. Minerals purchased are rounded down.

	19-05-2004 06:04									#34
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Heh, I never would've guessed Unit Hurry Cost would've generated so much discussion, although I should've guessed from the reams of posts generated last time.

At least no one this time around is confusing "polynomial" with "exponential".

Printed chart: this classic solution is both simple and accurate, but requires external hardware (paper) and has a limited number of entries.

However, limited entries isn't so big a deal: a 2x2-column cheat sheet could easily show ec buy values up to 100 units, and beyond a certain point buying becomes more expensive than shell-upgrading, anyway.

The "external hardware" is pretty lightweight, too. Certainly I've played countless games that required extensive notes, Star Control II coming immediately to mind, so a single piece of paper isn't the end of the world.

	19-05-2004 07:15									#35
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F4 - production
Total minerals - Minerals accumulated = minerals left
Base
minerals left - production + 10 = optimal # of minerals
Hurry
Rush Cost / Minerals Left = Cost per mineral
Cost per mineral * optimal # of minerals = ECs to rush
(Round up the cost in the last step if it is not an integer)

Not too bloody difficult.

	19-05-2004 08:07									#36
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It is better to err on the safe side and increase cost/mineral if just estimating.

Right now I don't have access to SMAX but I was thinking of a scenario where you have a 80 mineral unit (why that expensive, dunno) and already have 12 minerals in the box and you output 67 minerals so you need to buy 11 more minerals to complete it optimally. Problem is I don't know the hurry cost.

Anyway hopefully someone can provide me the hurry cost for that.

	19-05-2004 08:39									#37
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For a 80 mineral unit with 12 min completed and base production 67 min, that is 79 min completed next turn without rushing. Since you are still in the 2nd row the rush cost is going to be relatively high and not worth it. I would simply find a crawler to rehome or convert a specialist to worker or something similar to produce 1 or 2 more mineral, so that the base could finish production the next turn without rushing.

Did I pass your test?

	19-05-2004 12:30									#38
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I'd change to a 70 or 60 mineral unit and then upgrade it for 10 or 20 ecs.

-Jam

	19-05-2004 17:42									#39
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quote: Originally posted by Minute Mirage Is there a problem with just using Nethog's table? I have it printed beside me when I play and it takes me only a few seconds to look up the cost of rush building.

...it's actually MariOne's table (see original threads)...
THANKS!

	19-05-2004 17:49									#40
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quote: Originally posted by anarchie C = M^2 / 20 + 2M U = C / M U = M/20 + 2

it would all look that simple... except that the formula is NOT

C = M^2 / 20 + 2M

but actually

C = INT(M^2 / 20 + 2M)


and
INT(M^2 / 20 + 2M) / M
is NOT
= M/20 + 2
nor INT(M/20 +2)...

just for the sake of precision, if it's that you seek

if you content of approximation, others above have shown easier rule-of-thumb methods (depending on how many ecs you consider acceptable to waste)

	19-05-2004 19:37									#41
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quote: Originally posted by Jamski I'd change to a 70 or 60 mineral unit and then upgrade it for 10 or 20 ecs. -Jam

I bet it'll be at least 30 ecs for you to upgrade your unit dear Jamski. And you'll take one more turn to do that unless you do mass upgrade from workshop which is prohibited in some circumstances.

	19-05-2004 19:42									#42
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Then its cheaper to let the unit build. Its rarely economical to rush expensive units.

-Jam

	19-05-2004 19:47									#43
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quote: Originally posted by MariOne just for the sake of precision, if it's that you seek

If somebody really have some time to kill, perhaps he could calculate for us what kind of differences between the real precise formula and my approximate formula that we are looking at, at different circumstances.

	19-05-2004 19:48									#44
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quote: Originally posted by Jamski Then its cheaper to let the unit build. Its rarely economical to rush expensive units. -Jam

But you really should find that one mineral somewhere because you would be wasting about 56 minerals if you let it to be built in two turns.

	19-05-2004 19:57									#45
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quote: Originally posted by MariOne ...it's actually MariOne's table (see original threads)... THANKS!

Yes, I know that you deserve the credit. However, the table I'm using is called "Nethog's SMAC(X) Rush Reference Chart" so it would be a bit confusing to call it MariOne's table, don't you think?

	19-05-2004 21:17									#46
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quote: Originally posted by Santiago_Clause .....I've played countless games that required extensive notes, Star Control II coming immediately to mind.....

Ahh, I loved that game. I moved back in Jan, and I kept finding little scraps of paper with the coordinates to rainbow planets

	19-05-2004 21:20									#47
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If a unit costs 80 minerals, upgrading to it costs at least 80 energy. Buying a single mineral when 12 out of 80 have been produced costs

M = 68
Total hurry = M*M/20 + 2M = 367
Total/M = 5.397...
So pay 6 energy and buy a single mineral, or pay 60 to buy 11, if the 10 minerals on the next turn are worth 54 energy.

If you want 11 minerals, however, the cheaper way is to switch to a facility (losing a mineral), buy 25 minerals for 50 energy, and switch back to a unit, losing 13 minerals.

Simple, with a 4-function calculator. Possible without, but slower.

	19-05-2004 22:00									#48
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Thanks CT, very illustrative.

	20-05-2004 03:58									#49
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Thanks for having fun with my example. It was a bit uncommon but it highlights why unit costs annoys the heck out of me.

	20-05-2004 07:15									#50
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Maths is far from my strong point so perhaps someone can tell me if I have wastage or not. I do the following (as an example):

Cost to hurry a unit: 107EC's. Turns left to complete: 5.
107/5= 21.4. 107-21= 86. Pay 86EC's and the unit is finished next turn. I can generally do this in my head which is why I like it. It works, but am I losing a lot?

Hobbes

	20-05-2004 08:36									#51
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Assume you have 21 minerals remaining.
Then the hurry cost is 64.
First, say you are producing 7 minerals/turn. Then you will finish in 3 turns.
64 / 3 = 21.33
64 - 21 = 43, which is in fact the correct price to pay

Now, say you are producing 10 minerals/turn. You will still finish in 3 turns, and you will still pay 43 and buy 14 minerals. However, the optimal rush would have only bought 11 at a price of (64 / 21) * 11 = 33.52 -> 34

So what you are doing guarantees that you will complete the unit next turn, but is not optimally efficient. The most inefficiency occurs when, given that production will complete in N turns, increasing production by 1 would decrease the number of turns left.

	20-05-2004 10:32									#52
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Hobbes, your formula works great at 4 or more turns, at 3 it usually works, but at 2 turns you'll wind up overpaying. At least it's fail-safe: you'll never underpay using your formula.

HongHu, your C - 2P formula starts getting sloppy as base production passes 20 or purchase qty 10. The spreadsheet shows the first "waste", of 2 ec, buying 7 minerals at a base with 24 production. ("Waste" I've defined as any ec's spent beyond what will buy a surplus of 10.)

Enigma_Nova, your formula is exact but requires 3 inputs (minerals remaining, hurry cost, and base production). Another downside is the pocket calculator, which you'll need if you'd rather not divide such lovely specimens as 110 / 31 in your head. One cannot argue with an exact answer, though.

Vev, your answer is 60. Unit cost is 5.4, incidentally, so to buy just 1 unit you'd pay 6.

The spreadsheet I used to test HongHu's formula is a matrix, of mineral quantities purchased on the x axis ranging from 1-39 and base production on y ranging from 10-100. Each intersection has 2 values, the min and max optimum purchase values. This forms the "reference sheet".

Against it are compared the corresponding cells of the "test sheet". If the test value falls within the reference values at a given production & purchase qty, the formula "works" for that situation.

Here's the funny part: I wanted to use "real" numbers, unprejudiced by knowledge of how the formulas worked, and wound up with a matrix where the cost is affected by the base production! As you move up the x axis to higher purchase quantities along a fixed y-axis value for base production, the only degree of freedom left is minerals remaining, which increases as you move up the chart. To get useful numbers it looks like I had to compare apples to oranges!

We're not really comparing apples to oranges, though, because we don't really care what we're building, or even how much it lacks being done, we care how much it costs to buy an extra 3 minerals to finish building it. (If it really bothers you, you can always move diagonally! :P Pbbbt!)

	26-05-2004 05:33									#53
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Enigma_Nova, thanks for the great formula! Now why didn't I think of that?