Skill Experience division calculation?

[Lawndart Jedi]

How is the skill experience division calculation done? Something seams to not be working right as skills with the highest species aptitude are not leveling the fastest. Right now I have a Human Fighter that had dodging, spellcasting, and stealth all at zero. I have skills page in Manuel mode and Long Blades was just over 3. I turned on dodging, spellcasting, and stealth so they would each get 25%. The spellcasting was the first to get to level 1, while stealth was 0.7, and dodge was 0.4. The aptitudes are dodging 0, spellcasting -1, stealth +1. Shouldn't spellcasting be the last to reach level 1, not the first?

  Code:

Dungeon Crawl Stone Soup version 0.15-b1-123-g0918319 (webtiles) character file.

LawndartJedi the Covered (Human Fighter)            Turns: 1873, Time: 00:11:07

HP  39/41        AC  8     Str 17      XL: 5   Next: 10%
MP   5/7         EV  6     Int  9      God:
Gold 230         SH  9     Dex 12      Spells:  0 memorised,  6 levels left

rFire  . . .     SeeInvis .     a - +0 long sword
rCold  . . .     Clarity  .     b - +0 scale mail
rNeg   . . .     rCorr    .     c - +0 shield
rPois  .         rRot     .     (no helmet)
rElec  .         Spirit   .     f - +0 cloak
SustAb .         Warding  .     (no gloves)
rMut   .         Stasis   .     (no boots)
Gourm  .                        (no amulet)
MR     .....                    (no ring)
                                (no ring)

@: not resistant to hostile enchantments, extremely unstealthy
A: no striking features
a: no special abilities


You are on level 3 of the Dungeon.
You are not hungry.

You have visited 1 branch of the dungeon, and seen 3 of its levels.

You have collected 230 gold pieces.

Inventory:

Hand weapons
 a - a +0 long sword (weapon)
Missiles
 o - a throwing net (quivered)
Armour
 b - a +0 scale mail (worn)
 c - a +0 shield (worn)
 f - a +0 cloak (worn)
 p - a plate armour
Comestibles
 d - 3 bread rations
 i - a slice of pizza
 n - 2 beef jerkies
Scrolls
 g - 2 scrolls labeled XEYRUL ANAPSOQOGH
 h - 3 scrolls labeled FIUNLOAGYE
 j - 2 scrolls labeled YSCHAU VE XIA
 k - a scroll labeled THRADI BROJEHIE
 l - a scroll labeled MOIFIOLUBIA
 r - a scroll labeled AQISANK IBBA
 t - a scroll labeled ERHUARGHUFUSI
Potions
 e - a potion of might
 m - a lumpy blue potion
 s - a metallic pink potion
 v - 2 green potions
Books
 q - a book of Conjurations   
   
   Spells                             Type                      Level
   Magic Dart                         Conjuration                  1
   Searing Ray                        Conjuration                  2
   Dazzling Spray                     Conjuration/Hexes            3
   Fulminant Prism                    Conjuration/Hexes            4
   Iskenderun's Mystic Blast          Conjuration                  4
   Iskenderun's Battlesphere          Conjuration/Charms           5


   Skills:
 - Level 3.0 Fighting
 + Level 3.5 Long Blades
 - Level 4.0 Armour
 + Level 0.4 Dodging
 + Level 0.7 Stealth
 - Level 3.0 Shields
 - Level 1.0 Spellcasting


You have 6 spell levels left.
You don't know any spells.

Dungeon Overview and Level Annotations

Branches:
Dungeon (3/15)           

Altars:

Message History

The gnoll is severely wounded.
You block the gnoll's attack. The gnoll hits you but does no damage.
Your shield and scale mail prevent you from hitting the gnoll.
The gnoll is severely wounded.
You block the gnoll's attack. The gnoll hits you but does no damage.
You closely miss the gnoll.
The gnoll is severely wounded.
You block the gnoll's attack. The gnoll hits you with a club.
You closely miss the gnoll.
The gnoll is severely wounded.
You block the gnoll's attack. x2
You closely miss the gnoll.
The gnoll is severely wounded.
The gnoll closely misses you. You block the gnoll's attack.
You block the gnoll's attack.
You hit the gnoll.
You kill the gnoll!
Your Spellcasting skill increases to level 1!
You have reached level 5!
The gnoll hits you but does no damage. You block the gnoll's attack.

     #....g#..........
     #.#.#.###...###.#
     #.....# #...#
     ###..## #####
  #  ####.####       #
  ...#.......# #####.#
 # #.#.......# .......
 ..#....#.##)##.....#
......#.#...gg@...).#
  .#......##.##.....#     #
   #.#.......# .....#####.###
     #.......# ######.<.....#
     ###.#####      #.###.#.#
       #%#     ######.#   #
       #.#     #...(..#  .#
       #.#     #......##.##.#
       #.#######.###..%.....#


You can see 2 gnolls.

Vanquished Creatures
  A gnoll (D:3)
  3 adders (D:2)
  A worm (D:3)
  4 bats
  3 giant cockroaches (D:1)
  9 hobgoblins
  7 jackals
  2 ball pythons (D:2)
  5 giant geckos
  2 giant newts
  5 goblins
  10 kobolds
  2 quokkas (D:2)
  8 rats
  2 plants (D:1)
64 creatures vanquished.

Vanquished Creatures (others)
  4 toadstools (D:1)
4 creatures vanquished.

Grand Total: 68 creatures vanquished

Notes
Turn   | Place    | Note
--------------------------------------------------------------
     0 | D:1      | LawndartJedi, the Human Fighter, began the quest for the Orb.
     0 | D:1      | Reached XP level 1. HP: 18/18 MP: 1/1
    69 | D:1      | Reached XP level 2. HP: 14/24 MP: 2/2
   318 | D:1      | Reached XP level 3. HP: 27/29 MP: 3/3
  1106 | D:2      | Reached XP level 4. HP: 28/35 MP: 4/4
  1310 | D:2      | Reached skill level 4 in Armour
  1871 | D:3      | Reached skill level 1 in Spellcasting
  1871 | D:3      | Reached XP level 5. HP: 39/41 MP: 5/7


Action                   |  1- 3 |  4- 6 || total
-------------------------+-------+-------++-------
Melee: Long sword        |   176 |   102 ||   278
Throw: Javelin           |       |     9 ||     9
       Throwing net      |       |     1 ||     1
  Eat: Chunk             |     1 |     3 ||     4

[Patashu]

If you don't receive enough skill points to distribute them 'as expected' to all turned on skills on a given kill, the remainder is given randomly.

[tedric]

That seems like an incomplete explanation, because the kill that put Spellcasting over level 1 was a gnoll, which is only worth 14 XP (I think; this is all drawn from the wiki, so.) and 14 XP is not enough to make Spellcasting leapfrog the other skills by so much. With 4 active skills each receiving 25%, it's only a 2 XP remainder (consider also that there's a "skill point ratio" that by XL 5 makes 1 XP worth only 0.2 Skill Points).

Since it takes approximately 60 SP to get a -1 apt skill to level 1, XP remainders do not provide an obvious explanation of why Spellcasting received 60+ SP while Stealth with its +1 apt only received 29 SP. You'd need a pretty ridiculous run of "luck" to have Spellcasting randomly receive enough extra SP from remainders (which with 4 skills active can never be greater than 3 XP!) to outpace the other skills 2:1.

Which is not to say that it's impossible! The OP could simply be noticing the effect of a streak, and streaks naturally occur in long strings of randomized outcomes (in other words, it was bound to happen to some skill for some player eventually, given the law of large numbers). But if this is normal behavior (I haven't paid close enough attention to notice whether it is or not in my games) then there's something more at work.

[nilsbloodaxe]

I'm pretty sure that it works by randomly distributing chunks of skill points weighted by the skill training percentages, so, by chance, you got more chunks directed at spellcasting. Note that this is much more likely to happen at lower skill and character levels because you need fewer skill points to advance.

[tedric]

So like all of the XP from a particular kill (or several large chunks if there's a lot of XP) will go randomly to one of your active skills, weighted by the percentages on the % screen? That makes more sense than tiny remainders.

[nilsbloodaxe]

So like all of the XP from a particular kill (or several large chunks if there's a lot of XP) will go randomly to one of your active skills, weighted by the percentages on the % screen? That makes more sense than tiny remainders.

Yeah, exactly, though I don't really know the sizes of the chunks.