Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

I am starting a IG:AC and was starting a maths hammer on all weapons, for all tanks including the HQ and Tank aces with improved BS, then it hit me, i was running off the 4th edition rules for hitting and scatter and all that.

How do you do a maths hammer on weapons that scatter? for hitting and all the rest?

can anyone please help?

What are you thinking about, Russ Turrets vs Vehicles? The quick way, you need the size of the vehicle and you figure the chance you will get a hit.

Or you are talking about vs infantry formations.

I was trying to do it for MC's and tanks.

Can you run me through the formula or maths behind it, i asked my maths teacher and he didnt know how to do it, i gave him all the material to size, scatter, rules etc and still couldnt work it out

What you're asking for is still a bit vague.

Do you want the probability of a Monstrous Creature killing a Leman Russ in one round of battle, for example? Or do you want the average scatter range for an ordnance blast with BS 3? Without more constraints, it's impossible to point you towards the proper mathematical tools.

im trying to work out the probablity of a cannon (whether being earth shaker or conquerer, etc) of it hitting with BS 3 (or BS 4 for tank ace and HQ) and wounding a toughness 4 and save 3+ model. (including scatter)

and then apply with to the standard AV 12 and AV 14 tanks.

yeah I can do a quick one. I want to do a cool one for against infantry ... it's on my list. Along with ... like, learning to drive.

So how does this work. For Russes. 5" template. We'll say the hole is just the middle of it.

Monstrous Creatures are on a 60mm ( 2.36" ) base. The radius of said base is 1.18". The radius of the 5" template is 2.5". If it scatters ( 2.5" + 1.18" ) = 3.68", then it has scattered too much. So a hit on the scatter or a scatter <= 3" is a hit.

The chances of a hit on the scatter are 1/3.

The scatter is 2D6 - 3". So you need to roll 2, 3, 4, 5, 6 on the 2D6. The chances of doing so are ... (1 + 2 + 3 + 4 + 5 ) / 36 = 15/36. So the chances of hitting a Monstrous Creature are ...

1/3 + 2/3 * 15/36 = 0.6111

Just to check, which your 'maths' teacher would approve of, I am sure. Chance to miss is ... you need to fail your scatter, and you need to get a 8, 9, 10, 11 or 12 on the 2D6. So (5 + 4 + 3 + 2 +1) / 36 = 2/3 * 15/36 = 2/3 * 21/36 = 0.3888

Not bad. It is BS3, after all. Note it has not yet wounded. So the Battle Cannon will hit the Monstrous Creature more reliably than a Lascannon. And it is not even that big.

So now that I am all excited before going to bed ... I would say a Falcon has a radius of 4.5". Assuming the center dot is negligible, a scatter of 5" is too much, which would be a roll of 8 on the 2D6. So to hit:

= 1/3 + 2/3 * (1 + 2 + 3 + 4 + 5 + 6) / 36 = 0.7222

Pretty good. Again, it is higher than the Lascannon.

I might have made a mistake but I think it is OK.

-----
Just to illustrate what is going on, if you were aiming at a bigger nasty, like one of those Forge World things or another Gargantuan, say it has a base of 4.5".

Now in this case, the center does not have to be in the middle. So after the center leaves the base, there is another 2.5" of scatter. So it is 4.5" + 2.5" or 7". So a roll of 7" is a hit (we'll say) and a roll of 8" is a miss. Good reason for those bases to be in mm instead of inches. So for Monstrous Creatures you have to add the 2.5", for vehicles you do not. If you want to get fancy, you would add 1/2 of the small hole. You could also approximately permutate your scattering angles. Think of it like doing (I am going to lecture) 'Riemann integral' aka the 'Rectangle thing' where the skinnier the rectangles are, the better your approximation to the Integral, until you get to the point where you have a continuous integration.

So on the Falcon, it generally has a radius of 4.5". But for two arcs on the front corners there is a longer part. So say it is 15% of the model.

So you go ... 1/3 + 2/3 * ( 15% * ( ... ) + 85% * ( ... ) )

Before going to bed, I THINK I am doing that right. It is possible I am counting parts of the model twice.

I think your problem is that you really do need the hole over the vehicle, unless you are using some absurdly strong weapon, such as Strength D in Apoc.

So you really do need the hole over the model for vehicles, which reduces the allowable scatter down to 2ish", for large vehicles. So you need a 2,3,4,5 scatter for BS 3, and add a 6 for BS 4.

BS 3:
1/3 + (2/3 * 10/36) = .518518..., which is only marginally better than a lascannon (at BS 3).

BS 4:
1/3 + (2/3 * 15/36) = .6111..., which is worse than a lascannon at the same BS, but not by much.

For Indirect shot:
1/3 + (2/3 * 1/36) = .351851851... which isn't that good, you are basically going for a hit on the scatter die.

Of course, this would be totally accurate for the circular vehicle (of doom). You may have a little more allowance going one way as opposed to another.

A separate idea is to put the hole over one corner (such as a Land Raider) and say 1/4 of the scatters will give you a higher allowance for scatter, while going any other way you need no scatter to get a hit. However, that 1/4 will give you a good scatter result, as they even getting a 10 will probably still get a hit. I may measure a Land Raider to see how that would play out.

Stupid Mathammer!

Far, far too many variables to make it worth it's salt!

It is actually the opposite, the hole adds 1/2 of the hole radius to the allowable scatter, that is an example of the point I was trying to make.

What was confusing was the part at the end.

So here we go. In the Falcon's case, first approximation is this:

tacobake: wrote:So now that I am all excited before going to bed ... I would say a Falcon has a radius of 4.5". Assuming the center dot is negligible, a scatter of 5" is too much, which would be a roll of 8 on the 2D6. So to hit:

= 1/3 + 2/3 * (1 + 2 + 3 + 4 + 5 + 6) / 36 = 0.7222

Pretty good. Again, it is higher than the Lascannon.

I might have made a mistake but I think it is OK.

But you can make a second approximation. You do this by making various radiuses, and computing the individual probabilities at each one.

So right now everything other than 4.5" counts as a miss. But we can say that 15% of the ones within 6" count as a hit.

So at 4.5":

Sucess: 0.7222
Fail: 0.2778

Right now 100% of the rolls of 5 and 6 count as a fail. We want 15% of them to count as a success. So:

15% * 2/3 * ( 4 + 5 ) / 36 = 0.025

So the chance of success is now 0.7472
Fail: 1 - 0.7472 = 0.2528

What I was worried about was counting something twice or otherwise doing something stupid. But the way to do this is with a number of finite radii, approximating a perfect solution, similiar to a Riemann Sum.

http://en.wikipedia.org/wiki/Riemann_sum#Methods

So in conclusion, Battlecannons are more effective anti-MC and anti-vehicle shooting than a Lascannon. But comparable to a TL Lascannon. The pie plate is better against MEQ infantry, of course. Especially with the pinning test.

Arglebooster wrote:I think your problem is that you really do need the hole over the vehicle, unless you are using some absurdly strong weapon, such as Strength D in Apoc.

So you really do need the hole over the model for vehicles, which reduces the allowable scatter down to 2ish", for large vehicles. So you need a 2,3,4,5 scatter for BS 3, and add a 6 for BS 4.

BS 3:
1/3 + (2/3 * 10/36) = .518518..., which is only marginally better than a lascannon (at BS 3).

BS 4:
1/3 + (2/3 * 15/36) = .6111..., which is worse than a lascannon at the same BS, but not by much.

For Indirect shot:
1/3 + (2/3 * 1/36) = .351851851... which isn't that good, you are basically going for a hit on the scatter die.

Of course, this would be totally accurate for the circular vehicle (of doom). You may have a little more allowance going one way as opposed to another.

A separate idea is to put the hole over one corner (such as a Land Raider) and say 1/4 of the scatters will give you a higher allowance for scatter, while going any other way you need no scatter to get a hit. However, that 1/4 will give you a good scatter result, as they even getting a 10 will probably still get a hit. I may measure a Land Raider to see how that would play out.

crap, you're right. That is why you are not supposed to make important decisions at 4 am. The diamater is 4.5", making it 2, 3, 4, 5.

So for the 15% thing you are adding another inch.

So it becomes:

.518518 + 15% * 2/3 * (chances of rolling a 6) = 0.518518 + 0.15 * 2/3 * 5/36 = 0.5324

Tacobake wrote:So in conclusion, Battlecannons are more effective anti-MC and anti-vehicle shooting than a Lascannon. But comparable to a TL Lascannon. The pie plate is better against MEQ infantry, of course. Especially with the pinning test.

So the TL Lascannon is actually better.

Squig_herder wrote:im trying to work out the probablity of a cannon (whether being earth shaker or conquerer, etc) of it hitting with BS 3 (or BS 4 for tank ace and HQ) and wounding a toughness 4 and save 3+ model. (including scatter)

and then apply with to the standard AV 12 and AV 14 tanks.

So now you can take this and apply it to the tanks. Thing is, there is a finite number. You just determine the % radii of each " interval. So say on a Landraider (I am just guessing).

These scatters are 100%:
2", 3"

66%:
4"

15%:
5"

0%:
> 5"

So keeping in mind I hope someone is editing this, for the corner idea you go like this.

1/3 + 2/3 * ( chance to hit )

Chance to hit is this.

How big is it? 5" x 6" with a hypotenuse of 7"?

So 1/4 ( of the total circle) * ( 100% of 2, 3, 4, 5, 6, 7, 8 + 50% of 2, 3, 4, 5, 6, 7, 8, 9, 10 )

So:

1/3 + 2/3 * 1/4 * ( ( 1, 2, 3, 4, 5, 6, 5, 4 ) / 36 + 0.5 * ( 1, 2, 3, 4, 5, 6, 5, 4, 3 ) / 36 )
= 1/3 + 2/3 * 1/4 * ( ( 0.8333 + 0.45833 ) )
= 0.5486

So compare to a 3" scatter as opposed to a 2" scatter on the Falcon.

1/3 + 2/3 * ( 1, 2, 3, 4, 5, 6 ) / 36 = 0.7222.

You would have to measure the different vehicles to do it right.

you know it might be possible to maximize the result by placing the template at a 'lagrangian point'. ooooooo .... everything is the '2/3 rule'.

I am an engineer. That means I don't need to get overly fancy. I looked at it like this:

1/3 automatic hit!

A typical vehicle is 3" across, so I can scatter 1" without problem, and offset placement means that a large portion of the 2" scatters hit. With BS3, that's like rolling a 5 or less (10/36) vs a 4 or less (6/36). So split the difference as some 3" scatters will hit due to length, and it's about 1/4 net on the remainder.

So it's about a 50% hit rate.

Thankyou so much, although it does take abit of read and rereading to get it

armored companys aren't playable in fith was my understanding. or was that just ardboys?

what do you when unplayable?

If you are talking about scoring units there is aforge world extension of the armoured company including some for of infanty

There's Armoured Company, from White Dwarf (and it was on the GW website), and then there's the Armoured Battlegroup from IA1.

The Armoured Battlegroup is a better list IMO - less silly rules like 'Aces High'.

BYE

So true and i would buy it if it wasnt from forge world and cost 20% of it's price to post

Just order more stuff. You need/want Vanquishers anyway.

Or just buy all the IA books in one go. That should have you hitting £250 easily enough.

BYE

Thats all well and good but when your 16 and spend all the money you save on orks and eldar it's pretty hard to to save up 250 pound especially in australian lol

I love me boyz and the other gits (my beloved ulthwe) lol

Just steal it from your parents. They won't notice.



Christmas is coming up soon as well. Now's about right to start asking for stuff.

BYE

HBMC: Giving quality advice since...err...yeah...

I always have the best advice when it comes to the Guard, even for things outside of the game, like getting rulebooks.

BYE