Vertical Line in Equation

I tried the ff equations:

abs a
lline a rline 

But its displaying rectangles instead of vertical line “|”. Im using LibreOffie

This sounds as if you haven’t installed the OpenSymbol font.

I guess that some stuff gets asked again & again:

The answer in all cases (install OpenSymbol font):

  1. Click on to download a file.
  2. In Windows Explorer double click on downloaded font file and click Install button at the top of window.
  3. Open LibreOffice Math and type in formula. Problem solved.