1. The choice between weapon skills is described correctly, but there's a side note: throwing skill doesn't get any weighting, that's why it's impossible to acquire blowguns.
2. Ranged weapons skills other than throwing get their 2*3 weighting too, therefore the chance to acquire a short blade would be (12*13) in (12*13) + 8*(2*3) ~= 76.5%.
3. Acquirement rarities of the weapons get multiplied by
cubed damage rating and divided by weapon speed, then also multiplied by 25/9 for quick blades and by 5 for unseen weapon types. These calculations get even more complicated for weapon categories which have both one-handed and two-handed weapons, but we don't care about this within our example. Acquirement weightings of all the short blades would be:
Dagger: 10*(4*4*4)/10 = 64
Quick blade (unseen): 5*(5*5*5)/7 * 25/9 * 5 ~= 1240.1
Short sword: 10*(6*6*6)/11 ~= 196.4
Sabre: 10*(7*7*7)/12 ~= 285.8
4. Finally, after calculating those weightings, the choice between the actual weapons is made according to them: each weapon type has a chance to be chosen equal to its weighting divided by the sum of all weightings.
Note to Siegurt: compound assignment operators in C++ return the result of the operation, so this piece of code
- Code:
if (x_chance_in_y(acqweight, count += acqweight))
result = i;
is the equivalent of
- Code:
count += acqweight;
if (x_chance_in_y(acqweight, count))
result = i;
An unseen quick blade has a 1240.1/(64+1240.1+196.4+285.8) ~= 69.4% to be chosen between all short blades. And the final answer is 69.4% of 76.5% ~= 53,09%.
Sunday, 28th July 2013, 07:28 
