Definition:Inner Product/Real Field

Definition
Let $\R$ be the field of real numbers.

Let $\GF$ be a subfield of $\R$.

Let $V$ be a vector space over $\GF$.

A (real) inner product is a mapping $\innerprod \cdot \cdot: V \times V \to \GF$ that satisfies the real inner product axioms:

That is, a (real) inner product is a complex semi-inner product with the additional condition $(4)$.

Also known as

 * Innerproduct

Also denoted as
$\innerprod x y$ is also denoted as $\left \langle {x; y} \right \rangle$.

If there is more than one vector space under consideration, then the notation $\innerprod x y_V$ for a vector space $V$ is commonplace.

Also see

 * User:Leigh.Samphier/Refactor/Definition:Real Inner Product Space


 * User:Leigh.Samphier/Refactor/Definition:Complex Inner Product


 * User:Leigh.Samphier/Refactor/Definition:Real Semi-Inner Product, a slightly more general concept.


 * The most well-known example of an inner product is the dot product (see Dot Product is Inner Product).


 * Definition:Hilbert Space