That's interesting. In v1.3.x and earlier, projects round up, and I don't see any changes to the projects aside from increasing the bonus from 5% per 10 manufacturing to 10% per 10 manufacturing listed in the changelog.

The projects have always more or less been step functions; the model, at least in 1.3.x and earlier, was ceiling(socialManufacturing / 10)*projectBonus. From what you're saying, it's now floor(socialManufacturing / 10)*projectBonus, which makes economic stimulus and research projects into even more of a trap than they already are.

The projects having a variable bonus is nothing new. It was like that in 1.3.x, 1.2.x. 1.1.x, 1.0.x, and as far back into the betas as the +X% output per 10 manufacturing project model existed, and even further back into the beta and alpha with the +0.25 output per manufacturing projects.

OK, after further experimentation, I was partially wrong.

The function for them now appears to be:

SP=social production

If SP > 0

0.05 * (1 + FLOOR((SP -10)/10))

That is:

0.1-9.9:  +5%

10 - 19.9: +10%

20-29.9: +15%

etc.

I still vote that it should be the simple:  CEIL(SP) * 0.01   or perhaps 0.05 + CEIL(SP/2) * 0.01

I'll recheck a formula.

But the observed values are as I (restated):  the bonus increments when you hit a multiple of 10.

Preferentially, I use DIV (integer division), so it appears to look like:

(1+ (SP DIV 10)) * 5%  when SP > 0

They should still change it to be a smoother gradient than the pretty harsh step function it is now.

The XML actually permits the divisor to be set to any number with no more than three digits following the decimal point which is less than or equal to (2^31 - 1)/1000. There are no issues during gameplay that I am aware of from setting the divisor to 0.001 manufacturing per bonus increment (assuming you've adjusted the bonus increment to account for the fact that you've multiplied the manufacturing output by 1000, anyways; an interesting side-note is that it appears that the game knows the manufacturing output down to at least the thousandths place).

I suspect that the variables in the project XML files are handled by the game as signed 32-bit integers, with the game treating the integer as the number of thousandths in the number that you wish to represent.

It won't quite make the bonus map directly to the social production; some rounding is performed after dividing the social manufacturing by the divisor set in the project file and before multiplying by the bonus. It does make the steps in the staircase function much smaller and so produces a smoother function.