I am using Views 3 and I was able to do some math on the fields using the "Views Custom Field" module that was recommended to me.
It works perfectly and does exactly what I want it to do, but my problem is that I need to grant access to users to create views and calculations on them. Views custom field is not really a math only field, it's basically allowing them to execute PHP code directly on my site, which I suspect is dangerous.
Also, another requirement is that they are not directly modifying the actual data, but creating a view for themselves(or to share) that derived from this data. That means the view they create must somehow be connected to their ID and not modify the master data.
I don't know if it is the best approach, but I was thinking of using something like phpexcel and exposing the tables so they can link to certain data; it seems complicated for me and even more complicated for the users.
How would you approach this?