
12 Mar 2008, 19:38  #1 (permalink) 
Shas'Ui
Join Date: Nov 2006
Location: Canada
Posts: 550

Mathhammer  Can't figure some things out
Hi all,
I was just doing some mathhammer for some new army ideas when I realised I forgot/couldn't figure out how to crunch some of my figures. I feel kinda chumpish as I'm sure I used to know how to crunch these numbers. :[ Does anyone know,
What I'm looking for is expected value figures for army design, not so much game mechanics for when I play. For example, the way I would caculate damage for say, a regular str8 weapon vs. AV12 would be: E(#hits) x E(#glance/#penetrate) x E(#destroyed) However, a melta gun, within 1/2 range gains an extra d6 to armor penetration, and I don't know how to factor that into the E(#glance/#penetrate) figure. Any (correct) help would be greatly appreciated, thanks.
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"That is not dead which can eternal lie. And with strange aeons even death may die."  Abdul Alhazred, The Mad Arab of Cthulhu Lore, on the subject of Chaos Tau [link] "Zomg, teh Tau are teh evil bastardz, they suk at life." copy and paste this into your sig if you hate Tau. Proud member of Team CMAP  DON'T HOLD BACK The time has come to GALVANIZE! 

12 Mar 2008, 19:45  #2 (permalink) 
Shas'Vre

Re: Mathhammer  Can't figure some things out
armour penetration for meltas within 12 are still just one d6, when wounding with cyclonic ion blaster, any roll of a six is ap 1. say you need 5's to wound, and I roll 2,3,3,5,6. I would have two wounds, and one at ap 1, and one at regular ap. the 6 being ap 1.
with gauss weapons, when you shoot at a vehicle, no matter what AV it may be, a roll of a six will be glancing. Say I fire three necrons as a rhino. front armour is 11. I roll three dice, and say it moved six inches. I need 4's. I get two hits. Now I roll two more dice, and if both or one is a six, its a glance, even though the strength and ap wont usually let me glance. Rending, I'm not to sure.
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12 Mar 2008, 20:16  #3 (permalink) 
Shas'Ui
Join Date: Nov 2006
Location: Canada
Posts: 550

Re: Mathhammer  Can't figure some things out
Well what I'm looking for is expected value figures for army design, not so much game mechanics for when I play. Sorry, I fixed some typos and such, so my question should be a little clearer now.
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"That is not dead which can eternal lie. And with strange aeons even death may die."  Abdul Alhazred, The Mad Arab of Cthulhu Lore, on the subject of Chaos Tau [link] "Zomg, teh Tau are teh evil bastardz, they suk at life." copy and paste this into your sig if you hate Tau. Proud member of Team CMAP  DON'T HOLD BACK The time has come to GALVANIZE! 
12 Mar 2008, 20:27  #4 (permalink) 
Shas'Ui
Join Date: Jul 2008
Posts: 984

Re: Mathhammer  Can't figure some things out
Rending is hard to figure because the odds of rolling a "6" improve depending on how many dice roll at a given time.
I found THIS to be a helpful tool to calculate the odds of rolling a 6. Maybe it will help. 
12 Mar 2008, 23:08  #5 (permalink) 
Shas'El
Join Date: Jan 2008
Location: Ota, Gunma Prefecture, Japan
Posts: 3,764

Re: Mathhammer  Can't figure some things out
In this, I'm giving you the chances of rolling particular values on dice, not expectations; I'm assuming that you can use the chances to generate your expected values.
The main difference between using a Melta at close range, and not, is the introduction of the bell curve of the result of 2d6 (as opposed to the linear progression of a single d6). In the following list, you get the chance of rolling an individual number on 2d6 (for the chances of glancing), followed by the cumulative chance of rolling that number or higher (for the chances of penetrating): [table] [tr][td]2d6 result[/td][td]Chance of rolling this number[/td][td]Chance of rolling this number or higher[/td][/tr] [tr][td]2[/td][td]1/36[/td][td]1[/td][/tr] [tr][td]3[/td][td]1/18[/td][td]35/36[/td][/tr] [tr][td]4[/td][td]1/12[/td][td]11/12[/td][/tr] [tr][td]5[/td][td]1/9[/td][td]5/6[/td][/tr] [tr][td]6[/td][td]5/36[/td][td]13/18[/td][/tr] [tr][td]7[/td][td]1/6[/td][td]7/12[/td][/tr] [tr][td]8[/td][td]5/36[/td][td]5/12[/td][/tr] [tr][td]9[/td][td]1/9[/td][td]5/18[/td][/tr] [tr][td]10[/td][td]1/12[/td][td]1/6[/td][/tr] [tr][td]11[/td][td]1/18[/td][td]1/12[/td][/tr] [tr][td]12[/td][td]1/36[/td][td]1/36[/td][/tr] [/table] Using your example of Strength 8 vs. AV12, I think it would look something like this: NonMelta: Chance of glance = 1/6, chance of penetrate = 1/3 Melta: Chance of glance (i.e. rolling a 4) = 1/12, chance of penetrate (i.e. rolling 5 or more) = 5/6 As an aside, this ignores the special rule that AP1 weapons get, but I'm sure you can work that into here without much work. For Rending, you can use the following list for the chances (like before, you have the chance of rolling an individual value followed by the chance of rolling that value or higher). [table] [tr][td]AP roll[/td][td]Chance of rolling this number[/td][td]Chance of rolling this number or higher[/td][/tr] [tr][td]1[/td][td]1/6[/td][td]1[/td][/tr] [tr][td]2[/td][td]1/6[/td][td]5/6[/td][/tr] [tr][td]3[/td][td]1/6[/td][td]2/3[/td][/tr] [tr][td]4[/td][td]1/6[/td][td]1/2[/td][/tr] [tr][td]5[/td][td]1/6[/td][td]1/3[/td][/tr] [tr][td]6[/td][td]0[/td][td]1/6[/td][/tr] [tr][td]7[/td][td]1/36[/td][td]1/6[/td][/tr] [tr][td]8[/td][td]1/36[/td][td]5/36[/td][/tr] [tr][td]9[/td][td]1/36[/td][td]1/9[/td][/tr] [tr][td]10[/td][td]1/36[/td][td]1/12[/td][/tr] [tr][td]11[/td][td]1/36[/td][td]1/18[/td][/tr] [tr][td]12[/td][td]1/36[/td][td]1/36[/td][/tr] [/table] For both the Cyclic Ion Blaster and Gauss weaponry, it would involve more calculations specifically based around the target's Toughness/Armour Save and Armour Value (respectively). Did you want me to try and calculate those? I hope this helps. Edit: Found how the table function works, and edited the tables so that they're easier to read.
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[table][tr][td]Regards, MT.[/td][td] [[/td][/tr][/table][hr]What's an abelian group with an associative, distributive secondary operator and the power to corrupt mortals? [spoiler=Answer]The One Ring![/spoiler] [hr] 
13 Mar 2008, 16:32  #6 (permalink)  
Shas'Ui
Join Date: Nov 2006
Location: Canada
Posts: 550

Re: Mathhammer  Can't figure some things out
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Yeah, just having the probabilities to wound/glance/penetrate help a whole lot for Mathhammer. I totally didn't think about using a normal distribution for the melta, as I figured it could be done through just binomials. (Hopefully that little statement of mine just made sense!) As far as I can tell right now, your calculations seem correct. Anyway, these calculations are probably a little more complicated than what the typical 40k'er is used to, so if you wouldn't mind, could you also try to crunch the CIB and Gauss figures as well? They may come in handy as a general reference. Thanks, man! I suppose if this thread gets developed enough, I could ask one of the mods to consider stickying it for general reference.
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"That is not dead which can eternal lie. And with strange aeons even death may die."  Abdul Alhazred, The Mad Arab of Cthulhu Lore, on the subject of Chaos Tau [link] "Zomg, teh Tau are teh evil bastardz, they suk at life." copy and paste this into your sig if you hate Tau. Proud member of Team CMAP  DON'T HOLD BACK The time has come to GALVANIZE! 

13 Mar 2008, 17:29  #7 (permalink) 
Kroot Shaper
Join Date: Aug 2007
Posts: 94

Re: Mathhammer  Can't figure some things out
For rending it works like this
A = chance to hit excluding rending B = chance to rend C= # of shots W= chance to wound F = chance of failing a save So expected wounds works out to be C*A*W*F + C*B For gauss weapons the chances to destroy a vehicle are A = chance to hit not including a roll of 6 B= hitting with a roll of 6 C = chance to glance D = chance to penetrate E = chance to destroy a tank on a glance (1/6) F = chance to destroy a tank on a pen (4/6) N = number of shots So the equation for expected number of vehicle destroyed results is N*A*(C*E + D*F) + N*B*E 
13 Mar 2008, 18:09  #8 (permalink)  
Shas'Vre

Re: Mathhammer  Can't figure some things out
put it in a table or a stem and leaf diagram
for the meltagun here's the table 0 1 2 3 4 5 6 1 10 11 12 13 14 15 2 11 12 13 14 15 16 3 12 13 14 15 16 17 4 13 14 15 16 17 18 5 14 15 16 17 18 19 6 15 16 17 18 19 20 one dice on the top the other on the side. apply it to any vehicle you want to each time it sais an equal value to the armour you're attacking that's 1/36 that it'll glance and each time it sais one that's over the armour you're attacking that's 1/36 to penetrating a stem and leaf is when you split the probability down to each thing that can happen and put the probablility on it. I'll draw one for the cyclic ion blaster against tactical marines to hit roll  1/2 miss  1/2 hit on a hit make a to wound roll to wound roll  2/3 fail  1/6 wound  1/6 semi rend, killed on a wound roll an armour save armour save roll  2/3 fail  1/3 wound, killed to work out the probabablity of any one thing happening multiply all the fractions leading up to it, if you want to find out how many times something should happen if you try it multiple times (like the CIBs four shots) multiply the whole thing by the number of shots or whatever. any more mathhammer ask me, I do it better than my dad who's qualified to teach maths!
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13 Mar 2008, 18:21  #9 (permalink) 
Shas'El
Join Date: Jan 2008
Location: Ota, Gunma Prefecture, Japan
Posts: 3,764

Re: Mathhammer  Can't figure some things out
Okay, let's give this a shot.
For the CIB, the easiest way, I suppose, would be to use the standard range of targets, i.e. GEQ (T3, 5+), MEQ (T4, 3+), and TEQ (T4, 2+). For a GEQ, the chance of any individual hit killing is 1/2. For a MEQ, the chance of any individual hit killing is 1/6*1/3 + 1/6 = 4/18 = 2/9 For a TEQ, the chance of any individual hit killing is 1/6*1/3 + 1/6*2/3 = 3/18 = 1/6 I'm still working on the other calculations.
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[table][tr][td]Regards, MT.[/td][td] [[/td][/tr][/table][hr]What's an abelian group with an associative, distributive secondary operator and the power to corrupt mortals? [spoiler=Answer]The One Ring![/spoiler] [hr] 
13 Mar 2008, 18:26  #10 (permalink)  
Shas'Vre

Re: Mathhammer  Can't figure some things out
uh for a gaurdsman it hits on a 4+, wound on a 4+, ignoring armour in a six. if armour isn't ignored they have a 5+ save
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