## Friday, July 9, 2010

### Italics in Math Equations

I've seen plenty of papers in the literature with equations that are practically unreadable. My main issue is that these manuscripts fail to follow a very simple guide in mathematical notation:
If the term in question is a variable, then it should be italicized. All other terms should NOT be italicized.
Do NOT Italicize:
• function names (sin, cos, log, ln etc...)
• dimensionless numbers (Re, Pr, Ra...)
• exact infinitesimal increments (dx, dy et... in BOTH integrals and differentials)
• descriptive text

Here are some examples:
Another special case is with indices. The same rules still apply so that if the index is a variable, then it must be italicized. If it refers to a type of procedure (e.g. average, maximum...) it should NOT be italicized. If it refers to an entitye (e.g. gas, fluid, solid, particle...) then it should NOT be italicized. Some examples include
In the last two examples, g and d refer to gas and particle diameter, respectively. Here, I am assuming that the particle diameter is a constant.

Voila!

Hope that helps a bit. If you think of something else, please feel free to add.

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