Axis of rotation
= Axis of rotation
{title2=$R\mathbf n=\mathbf n$}
= Rotation axis
{synonym}
The fixed <straight line> of a nonidentity three-dimensional <rotation>. For a <rotation matrix> $R$, its <direction vector> is an <eigenvector> with <eigenvalue> $1$. A <unit vector> along it also specifies the positive sense of the <angle> through the right-hand convention.