I need to generate Excel documents with Ruby (from Rails) on a Linux machine. I know of Spreadsheet::Excel, but it doesn\'t support formulas, and uses a pretty old format.
How about https://github.com/randym/axlsx
This gem can easily generate spreadsheets in the OOXML format (Open Office XML)
How about opening a spreadsheet (Spreadsheet::Excel) with the formulae already populated. Entering data into the referenced cells will cause them to display the result.
https://github.com/cxn03651/writeexcel/
I have come across the gem simple_xlsx_writer.
You can see the example of how to use it over here.
Hope it helps.