Great Merchant Trade Mission returns not matching description

[Atanvarno]

I was just testing gold returns from Trade Missions in order to figure out some sort of formula for returns.
I started a Duel map, entered Worldbuilder, created one city for myself (my capital), and Indian cities for every tile to the west (20-25 cities)
Then I placed one of my Great Merchants in each of the Indian cities, exited worldbuilder and checked how much I was getting for a trade mission. For each of the Great Merchants I would get 900 gold. Same for the city next to my capital as for the city 15 or 20 tiles away.
Then I took the city 10 tiles from my capital and increased it to size 20, it still gave 900 gold.

The description of the Trade Mission says that the gold it gives depends on size of target city and distance from your capital. It doesn't seem to do that in this scenario.

Later I also tried to sign Open Borders with Gandhi, as well as running a turn or two. Everything was still the same.

I'm using the 1.09 Patch.

Does anyone have ideas about what I may have done wrong?

 

[MrCynical]

In a conventional game the amount of gold definitely varies for distance and size of the city you send the merchant to, so something in the way you've set this test up must be interfering with some unlisted factor. Is there a dependency on the turn number or era for instance? Or on the number of cities you have? These seem the two most obvious differences between your test and a normal game.

 

[Atanvarno]

Yes, I agree those two factors differ from a normal game, but in the description it has no mention of these two affecting it. And in any case they should affect it in addition shouldn't they? Rather than remove the variables of distance and size altogether?

Does anyone know how the gold is actually calculated? I tried to look in the code, but couldn't find it in any Python file (I searched across all files for MISSION_TRADE).

 

[warpstorm]

Since your GMs weren't spawned in a city they have no source.

 

[Atanvarno]

True, but according to the description that shouldn't matter either. What is supposed to matter is distance to your capital.

I did some more testing, on an established game with old cities, and this time I did get some different values. It does appear that the age of the city plays in, so I presume the 900 was some sort of minimum price.