# probability

## Make a yes-or-no decision with a given likelihood

The probablility P of something occurring is defined as the number of looked-for outcomes divided by the number of possible outcomes. For example, the probability that heads will show up on an unbiased coin flip is 1 (there is one instance of heads on the coin) divided by 2 (there are two possible outcomes, heads or tails), which means P = 0.5. With this definition, any probability can be described as a number in the range from 0 (impossible) to 1 (absolute certainty).

## Repeated notes at 6 related tempi, with different probabilities

This example (taken from Tutorial 37 in the original Max tutorials) demonstrates one way the passpct program, from the example "Pass a certain percentage of bangs", could be used. In order for this patch to work properly, you'll need to download that patch, passpct.maxpat, and store it in the Max file search path.

## Pass a certain percentage of bangs

To make a random decision between two things, you can use the decide object. To make a probabilistic decision between two things, with one thing being more likely than the other, you can use the random object to choose randomly from a larger set of numbers, then assign a majority of those choices to mean one thing (and the remaining minority to mean the other thing). An easy way to do this is with the < object.

## Random numbers without repetitions

The random object outputs a pseudo-randomly chosen integer. The range of possible numbers is determined by the number received in the right inlet (or specified as a typed-in argument). Each time random receives a bang, it will output one of n possible numbers, ranging from 0 to n-1. Because each number has an equal probability of occurring each time, there’s a possibility that repetitions will occur. If you wish to prevent repetitions there are two approaches.