# Source: cirosantilli/generalized-coordinate

```
= Generalized coordinate
{wiki}
The variables of the <Lagrangian>, e.g. the angles of a <double pendulum>. From that example it is clear that these variables don't need to be simple things like <cartesian coordinates> or <polar coordinates> (although these tend to be the overwhelming majority of simple case encountered): any way to describe the system is perfectly valid.
In <quantum field theory>, those variables are actually fields.
```