Productivity module issue

[ipvgbm1095]

I fairly state that I attach productivity module first and then put a stack of copper ore for smelting.

At first it seemed to be working properly with completely emptied productivity gauge with extra production, but as I progress further it seems like things are going slightly off from standard.

Factorio Screenshot 2019.03.13 - 17.52.50.23.png (1.53 MiB) Viewed 2441 times

From 2nd attempt it became like this, with slightly less gauge from additional production. I'm fairly sure at this rate each 5 smelting grants extra 1 plate for this, but it always ends up with 1 or 2 less plate from fully expected production.

I'm sure there was no electricity cutoff, which could have caused this sort of jittery from my experience, so I'm sure everything's perfectly set.

Is this what normally happens in Factorio? If not, what can I do to compensate that slight bits of extra productivity?

[bobucles]

It sounds like your typical floating point "off by .0000000001" situation. If you want that extra free bit better invest in the next recipe.

[Acacel]

It´s a known Problem, and as far as i know you can´t do anything against it

[FasterJump]

Why not buff the productivity by 0.001%?

Productivity module 1: 4% bonus becomes 4.00004% bonus
Productivity module 3: 10% bonus becomes 10.00010% bonus
4x Productivity module 3: 40% bonus becomes 40.00040% bonus

[leadraven]

What the hell. It's definitely floating point error, but it's possible to make an integer check each time recipe is done.
I'm afraid this math won't be corrected due to performance priority.

[DerGraue]

I do not know what you did exactly, but I just tested this.
1 new electric furnace, 2 prod modules, insert 1 stack ore: I got exactly 60 plates which is exactly what it should be.