Soccer simulation for a game

Question

I would like to build a simulation engine which can simulate a soccer (association football) match. It would be cool great if you could help me. What is important to me is t

Answer 1

I would suggest you convert all your probabilities to percentages:

function Chance($chance, $universe = 100)
{
    $chance = abs(intval($chance));
    $universe = abs(intval($universe));

    if (mt_rand(1, $universe) <= $chance)
    {
        return true;
    }

    return false;
}

Chance(25); // 25%
Chance(5, 1000); // 0.5%

Also I would only instantiate some probabilities with the conditions of others, example:

if ($attack === true)
{
    if (Chance(15 * $aggressivity) === true)
    {
        if (Chance(10 * $aggressivity) === true)
        {
            // red card
        }

        else
        {
            // yellow card
        }
    }
}

EDIT: I just home and I really need to go to sleep but after a quick glance at your edit I just had an idea that might interest you. What if, instead of using a adjustment value of 1, 2 or 3 don't you use the tactical position of the team? For instance, a team with a 4-4-2 would have less chances of scoring a goal against a 5-3-2 team than with a 3-3-4 team. Assuming that the placements are always triplets (X-Y-Z) it would be pretty easy to compare which team performs the best at defending, passing and scoring.

A simple formula could be something like this:

A: 4-4-2 (Defending Team)
B: 3-2-5 (Attacking Team)

The chance of B scoring a goal would be (4 / 5) ^ -1 = 0.2 = 20%, and the inverse (team A scoring) would be (3 / 2) ^ -1 = 0.5 = 50%. PS: This doesn't seem to make much sense now, but I'll try to give another look at it in the morning.

And another thing: after a red card why does the faulting team stays the same? It should get weaker (one player less) IMO.