# triangular: Factories for functions that convert numeric data into... In beerda/lfl: Linguistic Fuzzy Logic

## Description

These functions create functions with a single argument `x` that compute membership degrees of `x` to a fuzzy set of either triangular or raised-cosine shape that is defined by `lo`, `center`, and `hi`.

## Usage

 ```1 2 3``` ```triangular(lo, center, hi) raisedcosine(lo, center, hi) ```

## Arguments

 `lo` A lower bound (can be -Inf). `center` A peak value. `hi` An upper bound (can be Inf).

## Details

The arguments must satisfy `lo <= center <= hi`. Functions compute membership degrees of triangular or raised-cosine fuzzy sets. `x` values equal to `center obtain membership degree equal to 1, `x`values lower than`lo`or greater than`hi`obtain membership degree equal to 0. A transition of the triangular (resp. raised cosine) shape (with peak at`center`is computed for`x`values between`lo`and`hi'.

If `lo == -Inf` then any value that is lower or equal to center gets membership degree 1. Similarly, if `hi == Inf` then any value that is greater or equal to center gets membership degree 1. `NA` and `NaN` values remain unchanged.

`triangular()` produces fuzzy sets of a triangular shape (with peak at `center`), `raisedcosine()` produces fuzzy sets defined as a raised cosine hill.

## Value

A function with single argument `x` that should be a numeric vector to be converted.

Michal Burda

`fcut()`

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```tr <- triangular(1, 2, 3) tr(1:30 / 3) rc <- raisedcosine(1, 2, 3) rc(1:30 / 3) plot(triangular(-1, 0, 1), from=-2, to=3) plot(triangular(-1, 0, 2), from=-2, to=3) plot(triangular(-Inf, 0, 1), from=-2, to=3) plot(triangular(-1, 0, Inf), from=-2, to=3) plot(raisedcosine(-1, 0, 1), from=-2, to=3) plot(raisedcosine(-1, 0, 2), from=-2, to=3) plot(raisedcosine(-Inf, 0, 1), from=-2, to=3) plot(raisedcosine(-1, 0, Inf), from=-2, to=3) ```

beerda/lfl documentation built on Oct. 17, 2020, 8:57 p.m.