> ## Documentation Index
> Fetch the complete documentation index at: https://docs.abscissa.eu/llms.txt
> Use this file to discover all available pages before exploring further.

# Variables

> Learn variables and their features.

## Multicharacter variables

All variables in Mathsys are multicharacter. This means:

```ms3 theme={"dark"}
x = 2
# x is now 2

a = 3
# a is now 3

ax
# ax is an independent variable
# it is not a*x

a x
# this is a*x because of implicit multiplication
```

This is akin to how it works in programming languages.

## Valid variables

Variables must follow the regular expression `/(?i)(?!\b(?:inf|of|use|lim|Any|Infinite|Nexists|Number|Tensor|Undefined|Variable)\b)[A-Za-zº$%]+/`. This might change in the following update, removing the `(?i)` particle and expanding possible identifiers.

Note keywords excluded.

Variables matching exactly greek letters (e.g. `pi`), get transpiled to LaTeX on their symbolic form for representation purposes.