[SOLVED] Correct calculation of: %-Aura, reduced mana reservation, reduced mana gem

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Mark_GGG wrote:

Sorry for the delay, didn't find your post before I left work last night.

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beysl wrote:

I checked the source code of the mana reservation site linked before:
http://fogz.mine.nu:8080/poe_reserved_calc/

There, you can see that they first multiply the aura reservation with the mana multiplier of the gem and then round down:

Then this reservation is multiplied with the passives and rounded up:

This seems to be the correct calculation.

This is correct, because it always rounds down.

The first thing it calculates is the base cost of the skill, which is the cost of the skill gem and the multipliers of all support gems that make up the skill. This value must be an integer, and will be rounded down, because of how integer division works in computers. Anything after the decimal point is simply ignored.

Once it has be base cost of the skill, it calculates how much that is reduced by. Again it rounds down for the same reason - the reason you see it "rounding up" in your second step is simply that you're looking at the final cost/reservation, where what's actually being calculated and rounded is the amount taken off the cost by the reduction.

If you had blood magic and took the notable behind it, or otherwise obtained "less" mana reserved, this would be a part of the second calculation, where it's calculating the amount to take off the cost, but would stack multiplicatively with the "reduced" passives.

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ZigZog wrote:

Hi, bringing up an old topic because i faced an issue yesterday regarding mana reservation and was trying to find any explanation on why i had it.

18% mana reservation reduction on the tree plus a level 20 reduced mana (71% mana multiplier) result in 15+15+36+36=102% mana reservation instead of 14+14+35+35=98% mana reservation. This is a scenario where Mikelat's tool is wrong and I'd really like to know why if Mark could explain this result.