Definition:Matrix Scalar Product/Ring

Definition

Let $\struct {R, +, \circ}$ be a ring.

Let $\mathbf A = \sqbrk a_{m n}$ be an $m \times n$ matrix over $\struct {R, +, \circ}$.

Let $\lambda \in R$ be any element of $R$.

The scalar product of $\lambda$ and $\mathbf A$ is defined as follows.

Let $\lambda \circ \mathbf A = \mathbf C$.

Then:

$\forall i \in \closedint 1 m, j \in \closedint 1 n: c_{i j} = \lambda \circ a_{i j}$

Thus $\sqbrk c_{m n}$ is the $m \times n$ matrix composed of the product of $\lambda$ with the corresponding elements of $\mathbf A$.

The element $\lambda$ of the underlying structure of $\map \MM {m, n}$ is known as a scalar.

1965: Seth Warner: Modern Algebra ... (previous) ... (next): Chapter $\text {V}$: Vector Spaces: $\S 29$. Matrices