MathU™ RPN 2.2 for iPhone
Documentation
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Basic Operations
MathU RPN for iPhone supports both a portrait and landscape keypad. Simply rotate the iphone to switch between landscape and portrait keypads.
MathU RPN is based on Reverse Polish Notation (RPN). RPN differs from standard algebraic notation in that the numbers to be operated on are pushed onto a stack and then executed upon by a function. MathU RPN has a 16 or 4 element stack. In both cases, the first four elements of this stack are referred to by the names x,y,z, and t.
The value of the x register is what is displayed.
RPN works similar to the way you were probably taught to add numbers:
- First you wrote the two numbers above each other like this:
5 7 --
- Then you added the operator and wrote down the answer (I'm skipping the calculation part in your head)
5 +7 -- 12
In RPN you place the two numbers on the stack. To set up the same problem as above the keystrokes are 5 ENTER 7. This produces the stack picture:
just like what you put on the paper. The ENTER key pushes the current value up on the stack and allows you to put a new number in its place (The empty boxes will contain the values from previous calculations).
When you hit + the two values are added together. The + key always adds the x and y registers together and then places the result into x:
All the functions in MathU RPN work like this using values on the stack. Some like + work with x and y while others like SIN just use the value in the x register and replace it with the result. In this documentation, the former are called binary functions while the latter are called unary functions.
Hence the operation
12.5 + 7
is keyed as
1 2 . 5 ENTER 7 +
The ENTER key is used to separate the two values.
Most buttons on MathU RPN can access three functions. The function or number on the top of each button in white is accessed without shifts. The function just above the button in gold is accessed by pressing the f-shift key f before pressing the button (The f-shift indicator will light in the display when the f-shift is active). Similarly, to access the functions on the front of the buttons in blue use the g-shift key g. The g-shift indicator will light in the display when the g-shift is active.
Most functions remember the last x register value used during a computation. This value can be accessed via the LASTX function.
Copy and Paste
MathU RPN supports copying and pasting numbers from other applications on the iPhone and iPod touch. To copy the value currently displayed, double tap the display and then select "Copy" from the menu that pops up.
To paste a value into the display that was copied from another application, double tap the display and choose "Paste". If "Paste" is not available, it means that the system pasteboard does not contain a number recoginizable to MathU RPN.