i would like to defined a variable in lyx as per below screen shot.

enter image description here

I have tried to use the matrix in the equation however it is not working.

Can someone guide how I can do this please?

  • The curly brace witch separates a function into several parts is called a function with cases and in latex the command after the equal sign is \cases. I am sure if you search in lyx mah options you will find something about cases. If not you always can edit in code mode and use this answer : tex.stackexchange.com/questions/262079/…
    – koleygr
    Commented Sep 9, 2018 at 12:17

1 Answer 1


You can go to Insert > Math > Cases Environment. This will give the curly brace, and two horizontal boxes, with the cursor in the left box. Enter "1" into that box (the left one). Then press <Right> or <Tab> to go to the right box. Press <Ctrl + m> to be able to enter "text". Then type "if the individual is a member of group ". Note the space at the end. Then press <Right> to get out of text mode and back into math. Type \mathcal then <Space>, then A. Alternatively, you could have changed the font using the toolbar. Then press <Right> to escape from inside \mathcal{}. Then press <Ctrl + Return> to open a second row for the cases environment. You should see two new boxes on the second line, and you can proceed as before.

Note that you can do the above in many different ways. For example, you could have started the case enviornment by typing "\cases" and then , in math mode.

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