App for making and categorizing notes?

I'm a student at IT and need a clean way to make a database of equations for my math and electronics classes. Ideally I would like to be able to handwrite the equation and have it convert to text version, and store numerous equations for easy referencing. I have found apps that do just the handwriting but I can't save them to look up later, or I can't put them in a category. I'm new to iPhone and iPad and trying to sort through the hundreds of apps is giving me a headache. Hopefully someone out there knows of one I can use. Thanks for any help.

Added (1). Edit: fair enough HoovR, more than likely it'll be just a note taking app with handwriting in it. Even if I have to write the formulas in an odd way I just need to be able to save and categorize.

Added (2). Edit2: after hours of searching and sore eyes I found exactly what I need. For anyone else needing this type of app for whatever reason it's called TopNotes Pro. It lets me create separate notebooks and handwrite what I need to save in each one for quick and easy referencing later.

I think there would be so little demand for something like that I highly doubt if anyone would create that