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# unidcdf

Discrete uniform cumulative distribution function

## Syntax

p = unidcdf(x,N)
p = unidcdf(x,N,'upper')

## Description

p = unidcdf(x,N) returns the discrete uniform cdf at each value in x using the corresponding maximum observable value in N. x and N can be vectors, matrices, or multidimensional arrays that have the same size. A scalar input is expanded to a constant array with the same dimensions as the other inputs. The maximum observable values in N must be positive integers.

p = unidcdf(x,N,'upper') returns the complement of the discrete uniform cdf at each value in x, using an algorithm that more accurately computes the extreme upper tail probabilities.

The discrete uniform cdf is

$p=F\left(x|N\right)=\frac{floor\left(x\right)}{N}{I}_{\left(1,...,N\right)}\left(x\right)$

The result, p, is the probability that a single observation from the discrete uniform distribution with maximum N will be a positive integer less than or equal to x. The values x do not need to be integers.

## Examples

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### Compute Discrete Uniform Distribution cdf

What is the probability of drawing a number 20 or less from a hat with the numbers from 1 to 50 inside?

`probability = unidcdf(20,50)`
```probability =
0.4000```