RPN (Reverse Polish Notation) Calculator FAQ

Overview

Calculator features:

• Use of a 99-level stack.
• Can be started in an independent popup window.
• Work with variables using user-defined names (requires a java-enabled browser).
• Save user-defined variables in cookies for 50 days (your browsers must be set to allow cookies)..
• Use keyboard commands or calculator buttons to operate.

If the RPN calculator is not functioning properly, click here to understand why.

 

Basics

Arithmetical Calculations

Problem:

Log( 5 / (3⁵) )

Procedure:
 

Input:	Explanations:
5	The value 5 (numerator) is in the input field. The input may be done using the keyboard of your pc or the numerical block of the program.
Enter	The value 5 (numerator) is transferred into the first stack. The input field is now free to get the next value. 'Enter' can be done using the keyboard of your pc or the appropriate button of the program.
3	The value 3 (denominator) is in the input field.
Enter	The value 3 (denominator) is transferred into the first stack and pushes the values of the stack one level upwards.
5	The value 5 (exponent of the denominator) is in the input field. Here the value 5 can also be obtained performing a double click on the second stack (containing 5).
Enter	The value 5 (exponent of the denominator) is pushed into the first stack.
yx	The denominator 35 = 243 is calculated and pushed into the first stack. Beside of the stack the actual association to the variables 'x' and 'y' is shown. The command can be performed with the program button or using your keyboard (Input of 'yx' and 'Enter'). The keyboard command 'yx' is shown as tooltip when holding the mouse over the button yx. Using the button of the program makes the use of the last 'Enter' unnecessary.
/	The fraction 5 / 243 = 0,02057... is calculated and pushed into the first stack. The command can be performed with the program button or by pressing the '/' key on your keyboard. By pressing '/' the command is executed immediately without waiting for 'Enter' according to the HP-conventions.
log	The result Log(0,02057...)=-1.6866... is calculated and pushed into the first stack. The command can be performed with the program button or using your keyboard (Input of 'log' and 'Enter'). The keyboard commands are case sensitive and all lower case.

Handling the RPNcalculator can be done using the pc's keyboard or pressing the buttons on the calculator. Note, the keyboard commands must not be used as variable name.

To input a value in scientific notation (e.g., -1.2e-3 or 4.5e7), you may do one of the following:

• Standard RPN: 1.2e3, '+/-' or 'cs' to change the sign of the exponent, 'Enter' and '+/-' or 'cs' to change the sign of the whole value or
• RPNcalculator: 1,2e-3, 'Enter' and '+/-' or 'cs'.  To ease handling the '-' after 'e' will not be treated as arithmetic command (subtraction) but as sign (+/-).
   

Commands

Arithmetical Commands

Arithmetical commands can be input immediately behind a typed value.  No separation by 'Enter' is necessary. An arithmetical command is processed as soon as it is typed without waiting for 'Enter'.  This allows to add the values of 5 and 6 by: Type 5, 'Enter' and type 6+.  Arithmetical commands must not be contained in variable names.

Command	Calculate
^	Exponent yx
!	Factorial of x
%	x percent of y
/	Divide y/x
*	Multiply y*x
-	Subtract y-x
+	Add y+x.

Keyboard Commands

Keyboard commands are strings in the input field to be processed by 'Enter'.  Keyboard commands must not be used as variable name.

Command	Calculate
deg, rad	Adjust angle mode (degree or radians)
sin, cos, tan	Trigonometric functions
asin, acos, atan	Inverse trigonometric functions
log, ln	Logarithm with base 10 or e=2.718...
pi	3,14159...
ex	Inverse function for the natural logarithm: ex
div	Reciprocal 1/x
cs	Change sign: +/-
x2	Square: x2
yx	Exponent yx
r2	Square root of x
rx	x-th root of y:   y1/x
clear	Delete the stack and the input field
var	Open a variable listing in a popup window
up, down	Scroll the stack up or down
drop	Drop the stack one level
popup	Open a new instance or RPNcalculator in a popup window
=VarName	Save the 1.st stack in the user-defined variable 'VarName'
#VarName	Delete the user-defined variable 'VarName'
##	Delete all user-defined variables

User-defined Variables

Save and resume

User-defined variables are automatically saved in cookies for 50 days and will be resumed on starting a new instance of RPNcalculator.  To use automatic saving and resuming your browser must allow cookies. In your local home zone, after downloading RPNcalculator, this is usually allowed by the safety settings of your browser.  Defining, using and deleting user-defined variables is possible, even if cookies are forbidden.

Defining

User-defined variables are generated by writing '=VarName' (without inverted commas) into the input field and pressing 'enter'.  The variable will be stored with the value given in the first stack.  A variable name 'VarName' must begin with a character [a-z, A-Z] and may have arbitrary length.  Arithmetic commands '^!%/*-+' and keyboard commands are not allowed.  Already existing variables with the same name will be overwritten without request.

To store the value 5 in the variable 'five' perform the following: type 5, hit 'enter' button, type the equal sign followed by the word 'five' (i.e., '=five') and press 'enter' button again.

Using Variables

Call an user-defined variable by its name.  To multiply the value 6 with the above defined variable 'five' perform the following: type 6, hit 'enter' button, type the word 'five', and hit 'enter' button.  The variable value 5 of 'five' will be pushed into the first stack.  Now perform the multiplication by hitting '*' button.

Deleting Variables

User-defined variables are deleted using the command '#VarName'  and pressing the 'enter' button. To delete the above defined variable 'five' perform the following: type '#five' then hit the 'enter' button.  All defined variables can be deleted by '##' and hitting 'enter'.

Listing Variables

You may list all user-defined variables in a popup window by pressing the 'Var'-button of the program or by typing the keyboard command 'var' and hitting 'enter'.  Note: to work properly, your browser must allow popup windows.

The popup window lists all current variables and will not be updated when variables are defined or deleted. This allows you to hold listings of older variables on screen and to open several listings at the same time. You may transfer a variable or a value from the listing to the RPNcalculator by selecting and performing copy (Ctrl-C) and paste (Ctrl-V) to the input field.

History and Background Information

History

Reverse Polish Notation (RPN) was developed in 1920 by Jan Lukasiewicz as a way to write a mathematical expression without using parentheses and brackets.

Arguments for RPN

With the RPN-method, you first input the values and store them in a stack.  Then you give the operator that has to be applied to ,or performed on, the values.  This is equivalent to the way you add values by hand by first writing the values on the paper and then adding them.  Compared with the arithmetical method (i.e., most pocket calculators use this method), the RPN-method has more benefits:

• RPN saves time and keystrokes.  You never have to account for the parentheses while doing calculations.  The process is similar to the way you learned math on paper.
• You can see the intermediary results as you perform your computations rather than just the answer at the end.  This is an extremely helpful byproduct.  Math teachers are using this feature to improve student understanding of mathematics.
• An intermediate result allows the user to check the results and correct errors more easily.  It's easier to follow the stream of calculation.  The user defines the priority of operators.
• RPN is logical because the user first gives the number and then tells what to do with it.
   

Why doesn't this calculator work properly?

Javascript is used to perform the calculations and cookies save user-defined variables.  Depending on the settings, or preferences, of your browser, the following may not working properly.

• Saving of user-defined variables in cookies.
• Opening a popup window for the variable-listing.
• Opening of a popup window for a new instance of the calculator.

Please check your browser settings and adjust accordingly should you wish to use any of the features mentioned above.