9.4.3 Subscripts and Superscripts

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9.4.3 Subscripts and Superscripts

Subscripts are obtained either by the command

\sb{<maths>}

or by the special character:

_{<maths>}

Superscripts are obtained either by the command

\sp{<maths>}

or by the special character:

^{<maths>}

Examples:

This example uses \sb and \sp:

\[y = x\sb{1}\sp{2} + x\sb{2}\sp{2}\]
This example uses _ and ^

\[y = x_{1}^{2} + x_{2}^{2}\]
Recall from earlier that mandatory arguments only consisting of one character don't need to be grouped, so the above code can also be written as:

\[y = x_1^2 + x_2^2\]
This is simpler than the first two examples. However it's a good idea to be in the habit of always using braces in case you forgot them when they're needed.

All three of the above examples produce the same output:

Notice how the subscript gets tucked under the slope of the in:

\[ Y_{1}^{2} \]

Compare with

\[ Y{}_{1}^{2} \]

Example (Nested)

Subscripts and superscripts can also be nested (note that it is now necessary to group the argument to the superscript command):

\[ f(x) = e^{x_1} \]

which produces

This example isn't quite right as e isn't actually a variable and shouldn't be typeset in italic. The correct way to do this is:

\[ f(x) = \mathrm{e}^{x_1} \]

which results in:

If you are going to use e a lot, it will be simpler to define a new command to do this. The definition should go in the preamble:

\newcommand{\e}{\mathrm{e}}

Then in the document:

\[ f(x_1, x_2) = \e^{x_1^2} + \e^{x_2^2} \]

Take care when nesting subscripts or superscripts. The following

✘ x_1_2

will give a ! Double subscript error.

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