Function vector_dot

* Compute dot product of two vectors of equal lengths * * If \f$\vec{a}=\left[a_0,a_1,a_2,...,a_L\right]\f$ and * \f$\vec{b}=\left[b_0,b_1,b_1,...,b_L\right]\f$ then * \f$\vec{a}\cdot\vec{b}=\displaystyle\sum_{i=0}^L a_i\times b_i\f$ * * \returns \f$\vec{a}\cdot\vec{b}\f$ */