Damage formulae help please

Hi there I'm having a problem with damage formulas etc in VX ace. 

I'm trying to do the following: 

I have a defence of 13 and I want the monster to do around 2-4 damage with attack rating of 3. 

I want my character with attack of 16 to do around 7-9 damage to monster of 3 defence. 

How can I achieve this with formulas? Would fully appreciate help please I have a project I've been working on for over a year and I've only just started the combat stuff. Thanks in advance muzz

It's kinda odd because in the first example you want the defense to play a small rule and in the second you want it to play a large one.

On the other hand you don't need to give the same damage formula to enemies as you do your characters, so that would be doable, just make a seperate attack skill for them (actually you could give a different attack formula to every enemy, but that would be time consuming and you could run out of space).

But I think the best bet would be to work with the stat numbers, in the second example you would need something like {a.atk - b.def * 3} which works out perfectly, for that situation. But unless that stat differentual is going to stay similar throughout the game you will run into problem when the enemies get closer to the characters stat wise, or the characters pull further away.

The first example could be done with something like {a.atk * 5 - b.def}. But again, the more logical route would be to bring the enemy and character stat numbers closer together, unless there is a specific reason you don't want to do that.

Sounds to me - on the surface here - as though you want every attack to hit, and damage to be the only variable affected by attack rating and defence, as such... (If I recall correctly, Attack rating and Defence directly affects hit probability, not just damage, so...)
So, doing a little bit of quick mental work here, that means setting Hit Type to Certain Hit, and the damage formula should be... hmmm...
Part of the problem here is that that scaling is really... awkward, essentially risking rewarding low attack scores more than high attack scores...
Ah-HAH! Got it!
Try (20+(a.atk-b.atk))/4
Might want to add a bit of variance, as well.
Keep in mind, this doesn't scale well when the difference between attack and defense creeps much past 20... but if your game is based on generally low stats all around, this should work fairly reliably.

Maybe if I clarify a little... this is for a Phantasy Star 3 remake project thats been in the works for well over a year now :-D

All the mapping and character stuff is done and dusted. Pretty much just need to implement characters, combat and abilities.

In Phantasy Star 3 there are no dodges, crits or blocks. Every attack lands  but at low level you get your ass kicked and at higher level you still take damage but easily one shot enemies.

The first post I made was an example of the very first battle in the game and how the damage stats average from that encounter.

So thats the basic theory/calcuations to work it out from.

Ah, like so...
Well, make it ((20+(a.atk-b.atk))/4)+1, and the formula should guarantee a minimum of 1 damage, whatever the stats, at least. You still might want to consider calibrating the formula a bit according to how character stats scale.

Well the stats scale at around 2-3 damage and defence per level so what would you throw in their for that? thanks though your helps been very much appreciated! 

Hmmm, I'd simply suggest (for sanity's sake) scaling back progressions; say something along the lines of 3-4 in stats at level 1 and maybe 40-50 at top level, give or take. The autoscaling feature in the database handles that fairly easily.