Magery Skill % Chance Calculation

[iNFiNiTE415]

Ok, so I'm trying to write a magic tool for RunUO/Razor. I want to calculate the % chance of casting a certain circle based on the magery skill I'm getting from Razor.

If anyone knows or can double check this I would appreciate it greatly. Here is the algorithm I'm am using. It's based off of calculations I found in SkillCheck.cs and Spell.cs. I want these calculations to be the same as the ones in RunUO.

1) Calculate the minimum and maximum skill required for a circle.
2) Check if skill is in bounds.
3) Calculate percent chance.

ChanceOffset: Double = 20.0;
ChanceLength: Double = (100.0 / 7.0);

avg = ChanceLength * circle;
min = avg - ChanceOffset;
max = avg + ChanceOffset;

if (skill < min) then
  // too difficult
else
  if (skill >= max) then
    // 99% chance

chance = ((skill - min) / (max - min)) * 100;  // calculate % chance

[Phantom]

Plugin some test cases, see if it works out by hand, if it does what you want test it out in game.

[iNFiNiTE415]

Here is what I am getting from the algorithm.

Minimum and Maximum Magery Skill per Circle:

1st: min=-5.71428571428571 | max=34.2857142857143
2nd: min=8.57142857142857 | max=48.5714285714286
3rd: min=22.8571428571429 | max=62.8571428571429
4th: min=37.1428571428571 | max=77.1428571428571
5th: min=51.4285714285714 | max=91.4285714285714
6th: min=65.7142857142857 | max=105.714285714286
7th: min=80 | max=120
8th: min=94.2857142857143 | max=134.285714285714

This is the percent chance by circle to successfully cast a spell with the given magery skill. I've broken the results down by Skill in increments of 10. This would look much nicer in a graph which I will do once it's finialize.

MagerySkill=0
1st: chance=14.2857142857143
2nd+ 0% chance

MagerySkill=10
1st: chance=39.2857142857143
2nd: chance=3.57142857142857
3rd+ 0% chance

MagerySkill=20
1st: chance=64.2857142857143
2nd: chance=28.5714285714286
3rd: 0% chance

MagerySkill=30
1st: chance=89.2857142857143
2nd: chance=53.5714285714286
3rd: chance=17.8571428571428
4th+ 0% chance

MagerySkill=40
1st: 99%
2nd: chance=78.5714285714286
3rd: chance=42.8571428571428
4th: chance=7.14285714285714
5th+ 0% chance

MagerySkill=50
1st-2nd: 99%
3rd: chance=67.8571428571428
4th: chance=32.1428571428571
5th+ 0% chance

MagerySkill=60
1st-2nd: 99%
3rd: chance=92.8571428571428
4th: chance=57.1428571428572
5th: chance=21.4285714285714
6th+ 0% chance

MagerySkill=70
1st-3rd: 99%
4th: chance=82.1428571428572
5th: chance=46.4285714285714
6th: chance=10.7142857142857
7th+ 0% chance

MagerySkill=80
1st-4th: 99%
5th: chance=71.4285714285714
6th: chance=35.7142857142857
7th: chance=0
8th: 0%

MagerySkill=90
1st-4th: 99%
5th: chance=96.4285714285714
6th: chance=60.7142857142857
7th: chance=25
8th: 0%

MagerySkill=100
1st-5th: 99%
6th: chance=85.7142857142857
7th: chance=50
8th: chance=14.2857142857143

MagerySkill=110
1st-6th: 99%
7th: chance=75
8th: chance=39.2857142857143

MagerySkill=120
1st-7th: 99%
8th: chance=64.2857142857143

Once I test this ingame I will post my findings. If anyone else knows some of these numbers don't make sense please let me know.

Peace,
-Z