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EHP Maths

Author
Bearded Forum Alt
Republic University
Minmatar Republic
#1 - 2014-04-21 18:47:04 UTC
I noticed that the EHP given in fitting tools like EFT are a bit high. So, I started paying attention to how much damage I actually take before I explode. The actual damage taken on most of my lossmails seems a bit low. For example:

I have a t1 frig with 403 structure + 2381 armor + 518 shields = 3302 actual hp.
With just a DCUII running, it has 403(1.6) + 2381(1.23) + 518(1.12) = 4081 ehp
4081 ehp assumes worst case scenario, where damage is applied entirely to the lowest resists.
Last lossmail says that ship took 3691 damage.

So, where'd the other 400ish ehp go?
Thomas Builder
Center for Advanced Studies
Gallente Federation
#2 - 2014-04-21 19:28:42 UTC
Pretty certain that the damage in loss mails is actual damage after resists.
So it's actual HP + whatever you regenerated during the fight.
Plug in Baby
Broken Hearts Love Chocolate
#3 - 2014-04-21 19:37:23 UTC
You are comparing eHP and HP, you even make the distinction in your post.

You have (correctly) discovered that they are not the same thing.

This is not a forum alt, this is a forum main.

Bearded Forum Alt
Republic University
Minmatar Republic
#4 - 2014-04-21 19:59:14 UTC
Let me try again from a slightly different angle.

I'm confused about the lossmails, because it seems to me that 4081 damage should be the minimum amount on the 'damage taken' bit of the lossmail.

Why? Because any damage the ship takes will be reduced at least by the minimum amount of resists.

A silly example: pretend that you had a ship only with structure. It's got 100 hp.
Someone alphas it for 100hp; ships dies; lossmail reads '100 damage taken'.
Now go back and put a DCU on it. Ship has 100hp + 60% resists = 160 ehp.
Again, ship gets alphaed for 160 damage. Ship dies. Shouldn't the lossmail read '160 damage taken'? And wouldn't that be the absolute minimum that the lossmail could ever read?
JAF Anders
The Scope
Gallente Federation
#5 - 2014-04-21 20:00:26 UTC
Resists don't give you more hit points.

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Bearded Forum Alt
Republic University
Minmatar Republic
#6 - 2014-04-21 20:05:20 UTC
So, you're saying that the lossmail in the second case would still read '100 damage taken'?
Veskrashen
Deep Core Mining Inc.
Caldari State
#7 - 2014-04-21 20:30:15 UTC
EHP is based on an even split of all incoming damage types. On the killmail it displays actual damage taken.

For example, if you've got 1000HP of shields with no resist mods, you've got 33.75% average resists across all damage types, for about 1509 EHP. That's what would show up in EFT etc.

But if I smack you with nothing but EM damage, where you have 0 resist, you'll only take 1000 HP of shield damage before your shields fail. That's what would display on your killmail (for that portion of your total HP of course).

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Angry Mustellid
Lost Obsession
#8 - 2014-04-21 20:34:03 UTC
Also bear in mind EFT by default will give you an EHP reading based on uniform damage types.

In-game fitting panel EHP uses your lowest resist to calculate it.
Bearded Forum Alt
Republic University
Minmatar Republic
#9 - 2014-04-21 20:42:32 UTC
Veskrashen wrote:
EHP is based on an even split of all incoming damage types. On the killmail it displays actual damage taken...


Thanks for your reply, but I am not worried about the number in EFT. I'm sorry I even mentioned EFT, as it seems to have confused people about my question.

What I have been calling 'ehp' is the number I got by multiplying each layer of defenses on the example ship by that layer's lowest resist. Let's call this 'xhp'.

So my question is: shouldn't xhp be the minimum number that shows up on a lossmail? Of course, the number could be higher, given passive shield recharge and damage hitting higher resists, etc.

This is just intellectual curiosity.
Merdaneth
Angel Wing.
#10 - 2014-04-21 20:45:50 UTC
The damage always reads exactly what your ship had as raw hit points.

EHP are the resist multiplied by your raw hit points.

Another example: if you have high resists, a gun will do less damage to you per shot. Because that damage shown are the raw hp that you lose. After resists have been calculated.
Bearded Forum Alt
Republic University
Minmatar Republic
#11 - 2014-04-21 21:23:54 UTC
Merdaneth wrote:
The damage always reads exactly what your ship had as raw hit points.


Thanks. That makes sense.

I guess the difference, in the op example, between the raw hp of 3302 and the listed damage of 3691 is passive shield recharge? Looks about right, actually.
Gully Alex Foyle
The Scope
Gallente Federation
#12 - 2014-04-21 22:41:10 UTC
Yes, exactly.

Also worth mentioning that the dmg amounts that show on-screen during fights, both dealt (blue) and received (red), also are actual dmg.

So if you expect your own guns to deal, say, 500 alpha to a target standing still within optimal range, but read that you're doing only 300 per shot, it's because the target's resists (40% in this example) are applied to the figures. Naturally, same rules apply to the combat logs.

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Val'Dore
PlanetCorp InterStellar
#13 - 2014-04-22 02:54:36 UTC
The Shield/Armor/Hull hp values are the amount of damage you have to take to blow up. Resists just mitigate it.

So yes, your 100 hp no resist ship take 100 dmg to kill, and technically so does your 160 ehp ship:

100 HP 0 Resist hit by 200 dmg = 100 dmg taken, 100 excess dmg
100 HP 50 Resist hit by 200 dmg = 100 dmg taken, 0 excess dmg

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Rannasha Kore
Kore Inc.
#14 - 2014-04-23 13:02:08 UTC
Bearded Forum Alt wrote:

A silly example: pretend that you had a ship only with structure. It's got 100 hp.
Someone alphas it for 100hp; ships dies; lossmail reads '100 damage taken'.
Now go back and put a DCU on it. Ship has 100hp + 60% resists = 160 ehp.
Again, ship gets alphaed for 160 damage. Ship dies. Shouldn't the lossmail read '160 damage taken'? And wouldn't that be the absolute minimum that the lossmail could ever read?


This calculation is incorrect.

If a ship with 100 hp and 60% resist is hit by a 100 damage attack, it actually deals 40 damage (100 minus the 60% resisted). In this example, an attacker needs to do 250 damage to kill the 100 hp / 60% resist ship. Therefore we say that the ship has 250 effective HP (eHP).

Lossmails show the actual damage done after resists. In this example, it would show 100 damage, which is exactly the amount of HP that was burned. The eHP of the defender is not reflected in the lossmail.
Bearded Forum Alt
Republic University
Minmatar Republic
#15 - 2014-04-23 18:06:54 UTC  |  Edited by: Bearded Forum Alt
Rannasha Kore wrote:
Bearded Forum Alt wrote:

A silly example: pretend that you had a ship only with structure. It's got 100 hp.
Someone alphas it for 100hp; ships dies; lossmail reads '100 damage taken'.
Now go back and put a DCU on it. Ship has 100hp + 60% resists = 160 ehp.
Again, ship gets alphaed for 160 damage. Ship dies. Shouldn't the lossmail read '160 damage taken'? And wouldn't that be the absolute minimum that the lossmail could ever read?


This calculation is incorrect.

If a ship with 100 hp and 60% resist is hit by a 100 damage attack, it actually deals 40 damage (100 minus the 60% resisted). In this example, an attacker needs to do 250 damage to kill the 100 hp / 60% resist ship. Therefore we say that the ship has 250 effective HP (eHP).

Lossmails show the actual damage done after resists. In this example, it would show 100 damage, which is exactly the amount of HP that was burned. The eHP of the defender is not reflected in the lossmail.


Yes, thanks, I see where I was confused. As people tried to say even in the first few replies, resists don't add hp.
The 'potential' damage coming out of the attacker's guns aren't shown anywhere; only the hp subtracted from the target is shown.
EHP is the minimum amount of 'potential' damage the ship must take before it explodes; damage in the killmail/in combat logs is the amount of hp subtracted from the ship.

So if you know your resists, and the damage types that were being applied, you could figure out how much 'potential' damage had to come out of the attacker's weapons (i.e., their cumulative 'paper' dps)--which is how I got the higher number in the original example--but this, I now understand, is not the damage one takes, and not the damage that gets recorded.
Gizznitt Malikite
Agony Unleashed
Agony Empire
#16 - 2014-04-23 18:23:03 UTC
Bearded Forum Alt wrote:
I noticed that the EHP given in fitting tools like EFT are a bit high. So, I started paying attention to how much damage I actually take before I explode. The actual damage taken on most of my lossmails seems a bit low. For example:

I have a t1 frig with 403 structure + 2381 armor + 518 shields = 3302 actual hp.
With just a DCUII running, it has 403(1.6) + 2381(1.23) + 518(1.12) = 4081 ehp
4081 ehp assumes worst case scenario, where damage is applied entirely to the lowest resists.
Last lossmail says that ship took 3691 damage.

So, where'd the other 400ish ehp go?


Your math is wrong.

EHP take into account your resists.
Damage delt * damage reduction = HP damage

Rearraging this:
Damage dealt = HP damage / damage reduction == EHP.

Hull with a DCU2 Running has 60% resists.
The EHP of your hull == Hull HP / damage reduction == Hull HP / (1 - 60%) == HP / .4
For your above example, it is NOT 403 * 1.6, but 403 * 2.5
Gizznitt Malikite
Agony Unleashed
Agony Empire
#17 - 2014-04-23 18:32:13 UTC

There is a disparity in several programs in how they display your EHP, as the don't all handle the resistances of your hull the same.

Some simply average the resists you have to create a net "armor" or "shield" resist value.
EFT does this: So, if you look at a ship with shield resistances of 0, 20, 40, and 50%. Average them to 27.5%.
Then 1 / (1 - 27.5% ) == 1.379.
So your shield EHP in EFT == Shield HP * 1.379

This would the the damage needed to remove your shields assuming an even distribution of damage types. However, that never happens in game, and most ships have resistance holes, where weapons dealing the specific damage type deal more damage to your ship.
Princess Nexxala
Quantum Cats Syndicate
#18 - 2014-04-23 18:49:25 UTC
Well ****, I always thought an invuln added hit points to my ship. Way to burst my bubble you *******!

nom nom

Gully Alex Foyle
The Scope
Gallente Federation
#19 - 2014-04-23 23:29:33 UTC
Gizznitt Malikite wrote:

There is a disparity in several programs in how they display your EHP, as the don't all handle the resistances of your hull the same.

Some simply average the resists you have to create a net "armor" or "shield" resist value.
EFT does this: So, if you look at a ship with shield resistances of 0, 20, 40, and 50%. Average them to 27.5%.
Then 1 / (1 - 27.5% ) == 1.379.
So your shield EHP in EFT == Shield HP * 1.379

This would the the damage needed to remove your shields assuming an even distribution of damage types. However, that never happens in game, and most ships have resistance holes, where weapons dealing the specific damage type deal more damage to your ship.

^^ this

Assault frigs are a good example. On some hulls, even after putting some effort in plugging your holes (Shocked), it's not uncommon to have figures like 7,000 ehp to em dmg and 18,000 ehp to explosive dmg, making the average ehp value quite meaningless.

But if you wish, EFT allows you to set custom dmg profiles to calculate ehp instead of the default 'even distribution'. I often use it to check how big my holes are (ShockedShockedShocked).

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