In RobinHankin/freealg: The Free Algebra

set.seed(0)
knitr::opts_chunk$set(echo = TRUE)
library("freealg")

knitr::include_graphics(system.file("help/figures/freealg.png", package = "freealg"))

To cite the freealg package in publications please use @hankin2022_freealg. This short markdown document defines variables a, b, $\ldots$, z and their inverses A-Z, which are single-symbol freealg objects. At the end, it creates a file called lettersymbols.rda which loads these symbols in to an R session. This file resides in the `inst/' directory of the package.

Earlier versions of the freealg package included a copy of lettersymbols.rda in the data/ directory; lazy loading meant that all these letters adopted their freealg interpretation on loading the package, which is why this functionality was experimental. On reflection, however, it was not desirable and the file is not included in the package any more. Setting LazyData to TRUE in the DESCRIPTION file is not desirable either, because the dot object requires lazy loading to work correctly.

The following code creates upper and lower case single-letter symbols in an R session:

for(letter in c(letters,LETTERS)){
  eval(parse(text=paste(letter, ' <- as.freealg("',letter, '")')))
}

Lowercase letters c, q, and t, and uppercase letters C, D, F, I, T, present particular problems as they have distinct meanings in R.

With these variables we can do all sorts of slick calculations immediately after loading the package:

(1+a)*(1-a) == 1-a^2
.[a,.[b,c]] + .[c,.[a,b]] + .[b,.[c,a]] # Jacobi identity
horner(2*a+3*b, 1:4)

Package dataset {-}

Following lines create lettersymbols.rda, formerly residing in the data/ directory of the package.

save(
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,
A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,
file="lettersymbols.rda")

References {-}

RobinHankin/freealg documentation built on Dec. 24, 2024, 3:16 a.m.