of a point in a space
The vector going to this point from a certain point fixed in advance, which is called the origin.
The radius vector is also called the position vector.
If a system of axes is given through the origin having a basic system of directions $v_1,\ldots,v_n$, then the $i$-th coordinate of the position vector with respect to this affine coordinate system is determined by the factor $x_i$ such that $x_iv_i$ is the parallel projection of the position vector onto the $i$-th axis along the remaining directions.
Radius vector. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Radius_vector&oldid=31689