1

I’m writing a scientific text and I’m trying to conform to the ISO 80000-2 standard regarding mathematical notation. After going through the standard there are still two situations I’m unsure about:

Situation 1):

What is the proper typesetting format for variables denoted with subscripts? For example, given the following expression:

$x_{new} = x_{old} + 1$

Should the “new” and “old” text be italic/bold, uppercase/lowercase etc.? Are there any rules for this? ISO 80000-2 does not mention variable names including subscripts as far as I can tell.

Situation 2):

If $\mathbf{X}$ is a matrix, denoted in uppercase, italic, bold. And I want to refer to the first column vector of the matrix, should that be: $\mathbf{x}_1$? I.e., lowercase bold italic to indicate that this is a vector, not a matrix. Or should it be denoted as $\mathbf{X}_1$ to indicate that the quantity is taken from something which is a matrix? Or are both notations wrong?

Petahanks
  • 13

1 Answers1

3

You are using 

$x_{new}$

which is wrong anyways. Typeset 

$x_{\text{new}}$

to get $x_{\text{new}}$.

Michael Hoppe
  • 18,103
  • 3
  • 32
  • 49
  • Ok, thank you. So you are saying then that subscripts should be written in non-italic, non-bold, lowercase letters? Or is the choice of uppercase/uppercase up to personal taste? Also, are you basing this answer on a standard you can refer me to or is this just your opinion? – Petahanks May 07 '19 at 11:16
  • 1
    I don't know the standards, but I know if you don't surround them with the \text{} part you get then treated as variable names by default in effect with LaTeX and MathJaX. –  May 07 '19 at 15:33
  • https://en.m.wikibooks.org/wiki/LaTeX –  May 07 '19 at 17:47