Definition:Pointwise Addition of Linear Operators

Definition

Let $V$ be a vector space.

Let $\map \LL V$ denote the set of linear operators on $V$.

$+: \map \LL V \times \map \LL V \to \map \LL V: \forall S, T \in \map \LL V:$

$\forall u \in V: \map {\paren {S + T} } u := \map S u + \map T u$

where $+$ on the right hand side is vector addition.

Specific Instances

Specific instantiations of this concept to particular vector spaces are as follows:

Complex Vector Space

Let $\C^n$ be a complex vector space.

Let $S$ and $T$ be linear operators on $\C^n$.

Then the pointwise sum of $S$ and $T$ is defined as:

$S + T: \C^n \to \C^n:$

$\forall u \in \C^n: \map {\paren {S + T} } u := \map S u + \map T u$

where $+$ on the right hand side is complex vector addition.

Sources

• 2017: Amol Sasane: A Friendly Approach to Functional Analysis ... (previous) ... (next): Chapter $\S 2.1$: Continuous and linear maps. Linear transformations