Conventions

This documentation follows the following notations or naming conventions:

• coordinates inside a reference frame are noted $(\hat{x}, \hat{y})$ or $(\xi, \eta)$ while coordinates in the physical frame are noted $(x,y)$
• when talking about a mapping, $F$ or sometimes $F_{rp}$ designates the mapping from the reference element to the physical element. On the other side, $F^{-1}$ or sometimes $F_{pr}$ designates the physical element to the reference element mapping.
• "dof" means "degree of freedom"