One of the things that I was missing of the HP50g in the HP Prime is the ability to keep many functions available for solving - something like the function library.
One alternative is to create multiple copies of a solver app - each with a different function. This is not good for organizing your functions!
Another alternative is to enter them into variables - but then you need to have a very good memory to know what each variable does.
But there is a “proper” solution too. Eddie W. Shore (whose blog we have mentioned many times before) has created a free application that handles 47 well used functions. You just run the app, and then choose among the different functions. These are stored in variable E1, and prior to that, you get a description of what each component of the function does.
You can find and download the application here: