Welcome to the tutorial, let's get you familiar with TouchRPN! We'll start by taking a look at the interface, and seeing what's what. What you see is divided into 4 sections (and a help button!) as follows:
As you can see, the four segments are:
- Stack View: This is where you view the contents of the stack, where numbers are stored during calculations.
- Keypad: For entering numbers, basic stack operations, and simple math.
- Auxiliary Functions: For other functions.
- Menu: For changing the contents of the auxilliary function view.
- Oh, and the big red help button, that's how you view the help, and tutorial file. (that's what you're looking at!)
Of course, all of these segments are extremely important. For now, however, we'll be focusing on the keypad and stack views.
Step 1: Typing numbers
The first thing we'll get used to is typing numbers into TouchRPN. Begin by entering a number, let's say 42. Type the following buttons:
Notice that when you began typing, the numbers appear on the left side of the view.
This means that you are in "edit" mode, in other words, you are textually editing
the number. As soon as you hit ,
you can see the number switch over to the right side. This means that the
number is on the stack and if you were to begin typing another number, it would
create a new element, and you would see numbers appearing on the left
side again. Also, if the numbers are on the left, 
functions as a backspace, while when they are on the right, it deletes the botton
element on the stack.
Step 2: Arithmetic
Adding numbers is simple, simply type both in, and hit
.
This takes the bottom two numbers, adds them, and pushes the result back onto the stack.
The other operations are similarly simple, 
subtracts the bottom number from the one above it,
multiplies the bottom two elements,
and 
divides the second
to last element in the stack by the last element in the stack (last is bottom).
Step 3: Negative Numbers
You may hvae tried to use the button
to make a negative number, and noticed that it didn't work as you expected.
This is because represents
subtraction, a separate, but related, operation to making a number negative.
To make a number negative, you use 
,
which takes the bottom stack element and makes it negative. It functions similarly
for "edit" mode and "stack" mode (last element on the left, "edit", or on the right,
"stack").
Step 4: Floating Point Numbers
Once you're familiar with entering integers into TouchRPN, floating point numbers (numbers with a decimal). Simply use
and 
as you would in any
calculator. You may notice, when you push this value onto the stack:
- The number displayed has slightly different numbers when displayed on the right, versus the left.
- The number displayed has fewer digits displayed than you entered.
The numbers on the right are the "float-ified" version of the numbers on the left. You can see that TouchRPN has rounded off the last 4 digits of the number you typed! Fear not, the numbers are stored with approximately 100 digits of precision. You can gain access to some of those digits using the "display" screen. To get to this, hit the "D" button (I'll make some icons for it in a later version), for "Display". You'll now see 5 buttons along the top of the screen. Here's what they each do, and how to use them.
(Digits): Sets the number of digits to display.
For example, press 
, noting the number of digits
displayed. Now type "3" and hit , now only 3
digits (2 after the decimal point) are displayed!
(Engineering): Press this button to enter
engineering floating point display mode (exponents are always multiples of 3).
(Fixed Point): Enter fixed point mode.
Note that in fixed point, "digits" refers to the number of digits displayed after the decimal point.
(Scientific): Enter scientific mode.
(Shortest): Enter "shortest" mode, where
the shortest version (between fixed and scientific) is used.
Conclusion
Now you know the basics of RPN, and how to do the basic operations with TouchRPN.Back:Documentation Menu