Rather than the traditional algebraic or RPN methods of inputting commands, Napier works with complete expressions, so you donít have to think about whatís on the stack or where you are in parenthesis levels. Just enter and edit the expression, and when you are satisfied that it is correct, tap the ENTER key. If you get the expression wrong, Napier will try to show you what was wrong, and where in the expression the problem was found, so you can fix it.
These expressions can be arbitrarily complex, using function calls or sub expressions as inputs to other functions with no limit to the levels of parenthesis. Unlike traditional RPN or Algebraic calculators, there is no need to start from the innermost expressions and work your way out. Just enter the entire expression and evaluate it.
Start with the example:
1.5 * Sin(45)
But suppose the angle was actually the sum of two angles, you might want to evaluate:
1.5 * Sin(25 + 20)
Maybe one was the result of a function call:
1.5 * Sin(25 +ATan(.364))
And the value .364 was in memory 1 from some previous operation:
1.5 * Sin(25 +ATan(M1))
The point to all this, is that you can just enter what you want to evaluate as a complete algebraic expression without thinking about what the calculatorís input idiosyncrasies are. The scrolling command box, and the ability to edit anywhere in the expression by directly tapping the desired insert point, makes it quite practical.
UnEdit ñ If you enter or delete something in the expression, then realize it was a mistake, just hit the UnEdit key to reverse the previous edit. It is similar to an Undo key, but wonít undo things like changing memories, it only affects the command box and starts over when the ENTER key is tapped.
Move the insert point ñ If you want to edit other than at the end of the expression, just tap in the command box where you want to go to. The vertical bar insert marker will go there and further input will too. To get back to the end, just tap to the right of the last character. If you need to, use the horizontal scroll bar to move the view area over the entire expression. The virtual width of the command box is several thousand characters.
BSP Key ñ This behaves the same as the BackSpace key on a keyboard, it erases the character to the left of the current insert point. If you select a section of the expression by dragging over it with the stylus, the BSP key will delete it all.
CLR Key ñ This just clears the entire command box.
Copy, Cut, Paste ñ These are under the Tools entry in the bottom menu bar. They behave the same as with other standard windows programs. You can cut and paste between Napier and other Windows applications too.