triangles

Wrap C code to calculate Pythagorean triples.

Installation

You can install the development version of triangles with

# install.packages("remotes")
remotes::install_github("jonocarroll/triangles")

Example

This package is purely for demonstration purposes, supporting this blog post: https://jcarroll.com.au/2023/08/11/wrapping-c-code-in-an-r-package/

The wrapped C code involves many features I learned about so I built this package to support the blog post in an effort to capture as many as possible. The processes here are not new at all, but I found many of the existing resources to be either out of date or confusing.

The function triangles() takes a maximum hypotenuse length maxval and produces a data.frame() in R. The columns represent the lengths of the sides of a right triangle a, b, and c such that all of these are integers, along with the sum of these (the perimeter of the triangle)

library(triangles)

triangles(20)
#>   a  b  c sum
#> 1 3  4  5  12
#> 2 6  8 10  24
#> 3 5 12 13  30
#> 4 9 12 15  36
#> 5 8 15 17  40

This is a complete data.frame returned from C

x <- triangles(20)
str(x)
#> 'data.frame':    5 obs. of  4 variables:
#>  $ a  : int  3 6 5 9 8
#>  $ b  : int  4 8 12 12 15
#>  $ c  : int  5 10 13 15 17
#>  $ sum: int  12 24 30 36 40
x[x$sum > 20 & x$sum < 35, ]
#>   a  b  c sum
#> 2 6  8 10  24
#> 3 5 12 13  30

Various iterations of the C code can be found in inst/src.