First of all: Without studying the "User's Guide" the app is relatively worthless. This assistance is only available English, at least within the app. NeoCal turns a tablet or smartphone into an extensive scientific and financial calculators. The display is arranged in my opinion excellent and can can be "seen" in the truest sense of the word, so it is excellent to read. The review is due to several windows that can be selected at the bottom of the screen, always guaranteed. Which window you have to choose, you need to write, memorize, or try to. The same is true for the many functions. In scientific calculations, I prefer the "Reverse Polish Notation" (english: Reverse Polish Notation, RPN), which can be selected in addition to the normal key sequence. It is less prone to error than the alternative use of parenthesis levels. An abundance phyikalischer constants and conversion methods are built. The recording of keystrokes are possible. I use NeoCal only recently and would be a representation of the stack with maybe 4 lines instead of just one favor (so far always HP calculators, most recently HP 50g, the course has many other functions).
For the novice, a learning mode would be desirable, in which you get to see by pressing a function key explanation thereof. But that is not a defect and not given in other calculators.
