# Dictionary:Dot product

The dot product (also called **inner product** or ** scalar product**) of the vectors **Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \mathbf{X} = [x_1,x_2,...,x_n]}**
and **Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \mathbf{Y} = [y_1,y_2,y_3, ...,y_n] }**
is

**Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \mathbf{X} \cdot \mathbf{Y}= \sum_{i=1}^nx_iy_i=[x_1y_1+x_2y_2+x_3y_3+\ldots+x_ny_n] }**.

The **dot-product reverse** is

**Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://en.wikipedia.org/api/rest_v1/":): {\displaystyle \sum_{i=1}^nx_iy_{n-(i-1)}=[x_1y_n+x_2y_{n-1}+x_3y_{n-2}+\ldots+x_ny_1] }**.

Compare *cross product*.