Trade Formula

[Nemphis]

Greetings to all, this is my first post and I am making this post to get some information about the "real" Trade Formula('s).


So far I have seen alot of data on this subject and even some formula's on Trade. I must say that there is alot of confusion because of the different formula's posted.

Maybe we can start by saying all the facts about Trade and get them confirmed. These are the onces that I heard so far:

1)The amout of money gained by trading ( with this I mean the innitial amount gained ) will be added in beakers ( these are the science icons (press F6 ingame to see)) to your science.

2)The city size doesn't matter to both formula's for Trade. ( with both I mean the amount of trade gained and the amount of innitail money gained )

3)That there are different formula's for the small payoff's ( <255 gold ) and large payoff's. ( >255 gold )

§) Please post your own question about trade, also if you want to get your findings confirmed.


Next to these facts I would like to findout both Trade formula. ( if there is already one please post it here and explain the formula )

When we have found enough (confirmed) facts we will try to set up the formula('s).

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The fatal flaw in every plan is the assumption you know more then your enemy -Sun Tzu

[debeest]

Welcome aboard, Nemphis.

William Keenan has pretty thoroughly explored the delivery-bonus aspect of trade, beginning from work published by Robert Lancaster in the Scrolls of Wisdom, and has also worked on the ongoing-trade-bonus aspect. He laid out the delivery bonus quite clearly in a post within the last four months. I can't find the post itself, but I downloaded it, edited it slightly for what seemed like clarity to me, and put his lovely Net-based version into a simpler Word version, which follows:


Introduction

This paper presents an algorithm to calculate the amount of science and gold received when a caravan establishes a trade route with another city. The algorithm is divided into two sections, the basic formula and multipliers.

Basic Formula: Roundown ((BTA of SC + BTA of DC + 1) * (D +10) / 48.5)

BTA = Base Trade Arrows
SC = Source City
DC = Destination City
D = Distance
FD = Foreign Delivery

Base Trade Arrows: The number of trade arrows a city produces from worked city squares.
Source City: Home city of the caravan.
Destination City: The city to which the caravan is delivered.
Distance: The number of squares separating the source and the destination cities. Imagine Civ2-map turned by 45 degrees. Then you see that map is a simple grid of squares. Take the "rectangle" defined by the position of the unit and the position of the city (all sides of rectangle are built by squares connected by lines, not by edges). Distance = (length of longer side of rectangle) + 0.5 * (length of shorter side of rectangle)

Multiply the results of the Basic Formula by all the multipliers listed below, rounding the final result up, if necessary

Foreign Delivery Multiplier
X1 The Source City and the Destination City are both part of the same civilization.
X2 The civilization of the Source City differs from the civilization of the Destination City.

Continental Multiplier
X1 source and destination cities are on the same continent
X2 source and destination cities are on different continents

Freight Multiplier
X1 if the trade unit was not Freight
X1½ if the trade unit was Freight

Commodity Demand Multiplier
X1 any commodity not demanded
X2 Hides, Wool, Beads, Salt, Copper, or Dye
X2½ Cloth, Coal, Wine, Silver
X3 Silk, Spice, Gems, Gold
X3½ Oil
X4 Uranium

Road/Rail Multiplier
X1 source and destination cities are not connected (by the most direct route)
X1½ connected by road
X2 connected by rail

Navigation/Invention Discovery
X1 source civilization has discovered Navigation or Invention or the game turn exceeds 200
X2 none of these conditions met

Railroad Discovery
X1 if Railroad has not been discovered
X2/3 if Railroad has been discovered

Flight Discovery
X1 if Flight has not been discovered
X2/3 if Flight has been discovered

Superhighway Multiplier
X1 neither city has Superhighways
X1½ one city has Superhighways
X2 both cities have Superhighways

Airport Multiplier
X1 neither city has an Airport
X1 one city has an Airport
X1½ cities are on the same continent and both have Airports
X2 cities are on different continents and both have Airports


Slowthinker suggested, and I agree, that you can omit the "+1" from the base trades and that the "48.5" is actually just 48. I find that this formula is quite accurate, although strangely not always exactly right. I think the rounding down occurs after all other calculations, but I'm not sure.

Robert Lancaster also published a basic formula for the ongoing trade bonus, which again I think William Keenan has improved. If I understand correctly, it's basically (combined trade of the two cities plus 4) / 16. Double it for same-continent (rail?)road-connected cities. I'm pretty sure I'm leaving stuff out on this one, but I haven't seen it accurately and completely laid out anywhere. Corrections? Additions? William?

[Nemphis]

Thanks for the reply.

I had already read the formula he posted (good work by the way) but I checked it in a couple of games of myself and they were far from truth.

Both cities (both mine) were getting different amounts of trade.
When i used the formula on it there came a much higher amount of trade.

I think I have a explaination for all this:

My D was only 3 and the two cities had a widely spread trade (17 and 36).

Observations: I was getting the most trade in the city with the least trade (about 1.5 as much as the city that has most trade).


I am afraid that the trading isn't simply one simple formula but is composed of many. (for diff. D's and amounts of trade already in the cities)


Edit: Please explain how the D is calculated ths might be an important factor.

[Thoddy]

see also this thread:

http://apolyton.net/forums/showthread.php?s=&threadid=2483&highlight=trade

Robert Lancaster also published a basic formula for the ongoing trade bonus, which again I think William Keenan has improved

The formula is not fully correct. See my post from Nov. 23/2001 I have tested some hours and found several things depending on the go to order.

[debeest]

Nemphis, it's one formula with a lot of variables in it: city trade, distance, foreign, other continent, commodity, connection, era, etc. I, skeptic that I am and harping critic of the Scrolls of Wisdom formula, now bow down to William Keenan for having completely nailed the delivery bonus formula (with a tiny touch-up at the end by SlowThinker). If you calculate the formula correctly, you'll find it accurate.

Distance is an awkward, unintuitive calculation in Civ. Count squares "diagonally" (that is, NE/NW/SE/SW on the map) from one city toward the other until you're vertically or horizontally aligned with the target city. Then count vertically or horizontally as appropriate until you reach it, and multiply that latter distance by 1.5, rounding down. Add the two numbers: the "diagonal" distance plus (1.5 times the "orthogonal (?)" distance); that's the "distance."

Thoddy is right, the ongoing bonus is not fully described yet, and his post does contain valuable contributions that need to be incorporated into it.

[Nemphis]

Another question about the D.
Do you have to count the distance Between the city or do you count the city with it as well?

[debeest]

Include one city. So, start at zero inside one city and count with each square you move until you're inside the other city. View function is handy for this.

[Scouse Gits]

Woops debeest - close but no coconut - you multiply the diagonal distance by 1.5 not the orthogonal - there are two ways to calculate distance - if you take the rectangle with a city at opposite corners the distance is given by longest side + 0.5 times shortest side - this can be demonstrated as the same as 1.5 times diagonal + remaining orthogonal.


Caaaaa
-----a
-----C
6 + 0.5*3 = 7.5

C-----
-a----
--aaaC
1.5*3 + 3 = 7.5


Does this help?
for what it is worth I am convinced that the availability of a desired return working commodity impinges upon the result - and don't forget the beaker bonus is capped - by what is not certain - definitely you cannot get more beakers than are required for the next advance - there was some received wisdom at this site some two years ago that the cap was 2/3 of the remaining beakers - but this has never been verified...

[debeest]

SG, I think we're saying the same thing but using the words differently. Note that by "diagonal" I was referring to NE/NW/SE/SW on the map, whereas I think that by "diagonal" you quite reasonably meant "along the diagonals of squares connected by corners rather than by sides."

[Scouse Gits]

Yup -- we concurr -- I'm so used to the isometric view that I forget that the 'squares' run 'diagonally' -- how's that for double dutch??

[Nemphis]

"How is that for dubbel dutch"

dutch!?
I am dutch =)
what does the sentence mean?