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From: Janis Papanagnou <janis_papanagnou+ng@hotmail.com>
Newsgroups: comp.lang.awk
Subject: Re: 100 Random Single Variable Linear Equations
Date: Fri, 6 Dec 2024 21:01:20 +0100
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On 06.12.2024 14:38, Mike Sanders wrote:
> [...]
>  
> But I do wonder about: 5x vs. 5 * x or even (5 * x)... I've read so many
> opinions on this matter. If there an offical standard? I dont know.

In printed (math) textbooks an explicit multiplication operator is
normally omitted, so you see  5 x  (or 5x , but I prefer a visible
significant separation, if only to not mis-read "5x" as "5 times").
There's also expressions like  5 x 6  where the 'x' is another form
of the multiplication operator; but in math (algebra) this is an
inappropriate syntax since you typically have variables named 'x'.
The explicit operator '*' you see is just the common multiplication
operator that is used in computer programs, and it is often used in
technical communication to be able to formulate a clear syntax that
is unambiguous and easy to understand (and can be clearly parsed in
expressions).

For documentation I'd use the most obvious form that leads to least
confusion. It also depends on context, who's reading the text. It's
certainly easier (IMO) to grasp formulas like
  a x^2 + b x + c = 0
than
  a * x^2 + b * x + c = 0
especially if there are a lot of multiplication factors. But I may
be biased by education. For communication in computer contexts I'd
use the latter.

> One older book I have (from 1917!) has 1-2 paragraphs saying 5x without
> an intervening * is very bad form & yet, everybody seems to use it, at
> least here the USA.

It's amazing that the old book you're referring to mentions '*' as
multiplication. Were I live, either the multiplication operator is
omitted (in books), or explicitly written as '·' (middle-dot), and
rarely (often in classic mercantile contexts) they use 'x', which
is, typographically actually another character (the '×', a smaller
sized middle-x). The '*', as said, in computer contexts, but I've
never seen it in our math books (unless computer related).

If the '*' is [in the USA] suggested in books that would probably
explain the choice of that character for computer programs' syntax.

Janis

> [...]