You won't be able to catch Latias using a Love Ball. The Love Ball increases chances 8 times, but only if your pokemon is the same as the opponent but opposite gender. In other words, you need to be using a male Latias which doesn't exist! I don't think using a Latios will work.
Anyway I wouldn't worry about the exact formula. Just know what the balls do. I find the Dusk Ball is the best since you get 4x catch rate in caves or at night (that's when I play the game mostly anyway).
Also, sleep and freeze are better than other status conditions, they get 2x catch rate but paralyze, poison and burn are only 1.5.