Including equations in books
Equations are one of the trickiest things to take from manuscript to print. Adding them into a published book is something of a fine art. They come with different rules and potential problems to plain text. They're made even more complicated by the fact every writer puts them into their manuscript in a different way. So each instance needs very different handling and preparation as part of the typesetting.
How to prepare equations in your manuscript
Working in MS Word, there are a few ways to insert an equation. You can place it as an image, type it in normal text, add it with Word's built-in Equation Editor, maybe even use a third-party program like MathType.
Equation Editor is the best starting point. Properly inserted mathematics gives us something much more useful to work with when the book reaches InDesign.
But don't worry if you've included equations as images or normal text in Word. They may first need to be rebuilt as proper equation objects, but we can always do this for you as part of the project.
What are display equations
These are the more complex equations. You'll likely set them apart in their own paragraph with space above and below, and often label them (1), (2), etc. The paragraph will be large enough to display the largest symbols, and the equation may also have dividing lines and indices. All these make it much taller than a normal line of text.
The most important thing to remember when preparing display equations is to write the entire equation with the Equation Editor. Don't write part of it in normal text and part with the editor. You'll only end up with the whole equation needing to be retyped from scratch as a single equation object when it comes to typesetting time.
What are inline equations
These are the equations that you might see mixed in with the text. A good example would be, "Newton's second law of motion is F = ma; force is equal to mass times acceleration." Again, you need to write the terms in an inline equation as a single, proper equation object. Don't string them together with normal body text in between.
Bear in mind that if you try to place a big, multi line equation with a dividing line as an inline equation, it won't look very attractive. When it comes to typesetting, it will suddenly need much wider line spacing than all the lines of text around it, throwing out the style. Inline equations are only really suitable for simple, short equations. If it's too long or complex, we'd highly recommend you make it a display equation.
How to handle variables
Variables are simply letters you'd include throughout the book to reference a mathematical term. You won't always need to write variables as inline equation objects, but it is still important to keep them consistent with the font and styling used in other equations.
Book convention says that you should italicize any scalar variables, such as in T for temperature. It also says that you should bold but non italicize any vector variables, like F for force. This helps make the meaning of your variables clear and helps them stand out from regular text in a paragraph.
Getting equations into InDesign
Even if you've carefully created your equations using the right symbols, you'll still hit a hurdle when it comes to typesetting. Book designers don't use Word, so all those neat and finely honed equations need to make the journey into Adobe InDesign.
Thankfully, once they're in, the software handles mathematical expressions nicely.
What happens to equations in ebooks
If you intend to convert your book into an ebook, you'll need to consider certain things carefully before you start.
Ebooks make text "flowable." This means the words can fill the screen irrespective of what size device you're using. It also allows the text to be adaptive so that readers can change the font size, spacing, margins, and so on.
Display equations are usually straightforward. Inline equations are more problematic, however, because they need to fit neatly within the lines of text. Modern ebook formats handle mathematical content far better than they used to, but equations still need checking carefully across different devices.
Getting equations right
So there we have it. If you decide to, or have to, use equations in your book, it will mean some extra work for both you and for your designer. You need someone on your team who has practical experience of all these issues. With a bit of investment, a good designer can make sure your equations all look beautiful. And, even more importantly, present accurately! You can read more about this as well as all other aspects of our book formatting service.