# Tacnode (Cartesian coordinates)

## Description

A tacnode (also called a point of osculation or double cusp) is a kind of singular point of a curve. It is defined as a point where two (or more) osculating circles to the curve at that point are tangent. This means that two branches of the curve have ordinary tangency at the double point. A tacnode at the origin of the curve can be defined in Cartesian coordinates.

Related formulas## Variables

x | X-coordinate (dimensionless) |

y | Y-Coordinate (dimensionless) |