LyX left subscript in math formula

Question

Does anyone know how to make a subscript on the left hand side in LyX in a formula?

Answer 1

In LaTeX, without using any additional package, you could use

${}_x F_x$

to write _xF_x. Using this as the baseline approach, inside a math formula, insert a subscript to "nothing", followed by the "middle symbol", followed by another subscript.

Answer 2

The mathtools package defines \prescripts which is supposed to give the right spacing for left super/sub-scripts.The syntax of the command is \prescript{<sup>}{<sub>}{<arg>}. To implement it in LyX one should define a macro as follows: To get it, on the "TeX" box you write the following string (don't copy-paste as it won't work. While typing the script LyX will change e.g. \{ into the correct form of {})

 \prescript\{\#1 \{\#2 \{\#3

and in order for it to preview nicely, write in the "LyX" box

^\#1 _\#2 \#3

of course you can skip either the sup or sub script argument, but you still need to have an empty '{}' for it, e.g

Note that if you get a compilation error you need to tell LyX to load mathtools via Document->Settings->Math options.

Answer 3

Here's a solution that I found to be easier than Werner's, and not requiring the extra packages and macros that Ur's solution needs:

Simply press CTRL+SPACE to make a half-space, which allows you to make the desired subscript:

Then delete the halfspace!
Unlike Werner's solution, I never needed to click anything. My hands never had to leave the keyboard!