Talk:Scalar multiplication

Scalar-matrix multiplication

Scalar multiplication can apply to a matrix as well as a vector. It can probably apply to other mathematical structures but I can't think of any off hand. RJFJR 00:20, Dec 27, 2004 (UTC)

(Matrices are regarded as vectors, in abstract linear algebra.) JoergenB 13:59, 27 August 2006 (UTC)

Oversimplification?

The last sentences, about scalar multiplication over a non-commutative ring, are somewhat obscure. A module over such a ring is either one-sided or two-sided; and in the one-sided case, scalar multiplication appears either on the left or on the right side, noth both. In the commutative case, normally the modules (or vector spaces) are implicitly considered as equipped with two-sided scalar multiplication. Text book authors sometimes may forget to mention it, but it is employed e.g. in taking tensor products. Perhaps adding a link or two about modules would suffice? JoergenB 13:59, 27 August 2006 (UTC)

Scalar multiplication of Functions

This article doesn't mention that functions can also have scalar multiplication operations, which have a different meaning.--Qijiang ok (talk) 00:27, 16 February 2016 (UTC)

Scalar-vector multiplication

The field of scalars of a vector space has a multiplication which is not the topic of this article. The proper title is Scalar-vector multiplication. Of course in the context of linear algebra, a coordinate space is dependent on the field K supplying the n-tuples of the space. The scalar-vector product will be defined for any sub-field k ⊆ K. For an encyclopedia entry, the title should distinguish its contents from other interpretations, such as the multiplication in the field suggested by the current title. — Rgdboer (talk) 01:58, 12 December 2023 (UTC)

Hardcopy experiment

A dozen books were pulled off the shelf to see whether this misuse of the term binary operation was perceived by textbook authors writing linear algebra. Most of these works date from the 1960s when the course was an innovation, leading to more advanced study in university algebra. The phrase "scalar multiplication" was commonly used. However, John T. Moore (1968) Elements of Linear Algebra and Matrix Theory has this comment:

We prefer the terminology multiplication by scalars to the more customary scalar multiplication in order to avoid any possible confusion with another type of product which is variously called scalar product, dot product, or inner product. The student of abstract algebra may be disturbed by our reference to multiplication by scalars as an "operation" in the vector space V, and we have nothing but sympathy for this feeling. Indeed, a (binary) operation defined in an algebraic system regularly associates an element of the system with each pair of elements of the same system. In the case of the operation under discussion, however, one member r of the pair (r, α) is from the system of real numbers R, and the other member α is from the space V. (page 3)

Moore admits that his is an "adversely critical comment" that readers must absorb. — Rgdboer (talk) 01:08, 20 December 2023 (UTC)