# Documentation

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# unidinv

Discrete uniform inverse cumulative distribution function

## Syntax

`X = unidinv(P,N)`

## Description

`X = unidinv(P,N)` returns the smallest positive integer `X` such that the discrete uniform cdf evaluated at `X` is equal to or exceeds `P`. You can think of `P` as the probability of drawing a number as large as `X` out of a hat with the numbers `1` through `N` inside.

`P` and `N` can be vectors, matrices, or multidimensional arrays that have the same size, which is also the size of `X`. A scalar input for `N` or `P` is expanded to a constant array with the same dimensions as the other input. The values in `P` must lie on the interval [0 1] and the values in `N` must be positive integers.

## Examples

```x = unidinv(0.7,20) x = 14 y = unidinv(0.7 + eps,20) y = 15```

A small change in the first parameter produces a large jump in output. The cdf and its inverse are both step functions. The example shows what happens at a step.

## See Also

#### Introduced before R2006a

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