Notation ModSim

Rotation

The rotation matrix between frame $A$ and $B$ is the coordinate from $B$ to $A$, the opposite of what one might think.

$$v^A=R_B^A{v}^B$$

Vectors

Vector from $p$ to $q$

$${\vec{r}}_{q/p}$$

Vector from $p$ to $q$ express in $A$ frame

$${\vec{r}}_{q/p}^A$$

Common mistakes

Arithmetic on coordinate vectors expressed in different frames

$$\begin{array}{r}{v}^A+u^B\\ v^A\times u^B\end{array}$$