Calculator input methods
This mode of operation also makes it impossible to change the expression being input without clearing the display entirely.
The first version is for simple calculators, showing how it is necessary to rearrange operands in order to get the correct result.
[9][10] When discussing these problems, Harold W. Thimbleby has pointed out that button-operated calculators "require numbers and operation signs to be punched in a certain order, and mistakes are easy to make and hard to spot".
The result can be: The effects of operator precedence, parentheses and non-commutative operators, on the sequence of button presses, are illustrated by: These are only simple examples, but immediate-execution calculators can present even greater problems in more complex cases.
In fact, Thimbleby claims that users may have been conditioned to avoid them for all but the simplest calculations.
Infix notation is a method similar to immediate execution with AESH and/or AESP, but unary operations are input into the calculator in the same order as they are written on paper.
Reverse Polish notation is parenthesis-free, which usually leads to fewer button presses needed to perform an operation.
Note: The first example illustrates one of the few cases where reverse Polish notation does not use the fewest button presses – provided one does not rearrange operands.
As with standard infix notation, typing mistakes in the entered formula could be corrected using the same editor function as the one used when programming the calculator.
S I N ( 3 0 ) × C O S ( 3 0 ) ↵ Enter 16 For the second example, two options are given depending on if the BASIC programmable pocket computers have dedicated trigonometric keys[18] or not.
[19] The ten-key notation input method first became popular with accountants' paper tape adding machines.
Online tenkey training and certification tools are available as well,[22][23] and some businesses use ten key typing speed as an employment criterion.
Modern computer algebra systems, as well as many scientific and graphing calculators, allow for "pretty-printing", that is, entry of equations such that fractions, surds and integrals, etc.
The templates contain spaces for values or expressions to be entered, and empty values would typically result in a syntax error, making it more cumbersome to navigate than standard infix notation; standard infix notation is often an option on such calculators as well.
[28] HP calls this its Textbook display setting,[29] which can be used in both RPN and Algebraic mode and in both the Stack and in the Equation Writer application.
↵ Enter 12 For the second example, two options are given, depending on whether the calculators will automatically insert needed parentheses or not.
