A simple library for programmatically calculating probabilities and simulating scenarios of the rolling of a single die.

This library is a generic tool that generally follows the rules set out by 40k, but with no actual tie to the rule set of 40k.

For the purposes of this tool, a Roll is the actions performed to get a single result. Meaning that a roll may actually be two rolls if you re-rolled, but these two rolls are made with the desire for a single result.

All rolls are created using the RollBuilder class. Using the fluent syntax, configure the Die to use, the target, the reroll behaviour and a modifier to the roll.

This simulates and is written in the order you would do this if you were actually rolling the die. I want to:

• Roll a 6 Sided Die
• Targetting a 3+ on the die
• I will reroll ones.
• Add one ot the final roll in an effort to get to 3+

// The above scenario using the builder.
var roll = RollBuilder.WithDie(Die.D6)
    .Targeting(Target.ValueAndAbove(3))
    .WithReroll(Reroll.Ones)
    .WithModifier(1)
    .Build();

Now that you have a roll you can call two methods. You can calculate the probability that the roll will be a success or generate a scenario where a random roll will be provided to you.

It is important to note that Rerolling in this library takes place BEFORE the modifier.

To calculate probability, call the CalculateProbability method on the roll. This will return a decimal between 0 and 1 with the probability of the roll you have built.

var result = roll.CalculateProbability();

To run a simulation, call the Simulate method on the roll. This will use a random number generator and play through the roll that you have built. This will return a Roll Result which has properties that explain what happened during the roll's exectution.