# Expressions¶

HFD has a built in expression language that handles parameters, math and a handful of useful functions.

## Available functionality in expressions¶

`+-*/()`

Normal arithmetic operators.`sqrt(arg)`

Square Root of arg`distance(p1,p2)`

OR`distance(x1,y1,x2,y2)`

The distance between the points (x1,y1) and (x2,y2)`angle(p1,p2)`

OR`angle(x1,y1,x2,y2)`

The angle in degrees of the line described by p1,p2`mmToInch(arg)`

Converts to inches from mm`inchToMM(arg)`

Converts to mm from inches

## Parameters¶

Parameters in any expression are looked up based on the current context.

The order of lookup is as follows

Local attributes

Local params

Parent attributes

Parent params

… Repeat until Document

Document params