Calculator input methods: Difference between revisions

Revision as of 16:57, 16 April 2024

Revision as of 08:36, 17 April 2024

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|+ Examples

! Formula

! Keystrokes

! keystrokes

|-

! keystroke count

| <math>5524 -+ 3372</math>

| {{Keypress|1}} {{Keypress|5}} {{Keypress|+2}} {{Keypress|1}} {{Keypress|04}} {{Keypress|+}} {{Keypress|13}} {{Keypress|0}} {{Keypress|+7}} {{Keypress|12}} {{Keypress|0}} {{Keypress|1==}}

|-

| <math>1 + 2 \times 3</math>

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{{Keypress|1}} {{Keypress|+}} {{Keypress|2}} {{Keypress|×}} {{Keypress|3}} {{Keypress|1==}}

| 6

6

|-

| <math>\sin 30 + 2 \times \cos 30</math>

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{{Keypress|3}} {{Keypress|0}} {{Keypress|SIN}} {{Keypress|+}} {{Keypress|2}} {{Keypress|x}} {{Keypress|3}} {{Keypress|0}} {{Keypress|COS}} {{Keypress|1==}}

| 10

|-

| <math>5 - 3</math>

| {{Keypress|5}} {{Keypress|−}} {{Keypress|3}} {{Keypress|1==}}

| 4

|-

| <math>15 + 10 + 10 + 10</math>

| {{Keypress|1}} {{Keypress|5}} {{Keypress|+}} {{Keypress|1}} {{Keypress|0}} {{Keypress|+}} {{Keypress|1}} {{Keypress|0}} {{Keypress|+}} {{Keypress|1}} {{Keypress|0}} {{Keypress|1==}}

| 12

|}

The first<math>1 two+ 2 \times 3</math> examples have been given twice. The first version is for simple calculators, showing how it is necessary to rearrange operands in order to get the correct result. The second version is for [[scientific calculator]]s, where [[operator precedence]] is observed. Different forms of operator precedence schemes exist. In the '''algebraic entry system with hierarchy''' ('''AESH'''),<ref name="Ball_1978" /> the precedence of basic mathematical operators is taken into account,<ref name="Ball_1978" /> whereas calculators with '''algebraic entry system with parentheses''' ('''AESP''')<ref name="Ball_1978" /> support the entry of parentheses.<ref name="Ball_1978" /> An input scheme known as '''algebraic operating system''' ('''AOS''')<ref name="Ball_1978" /> combines both.<ref name="Ball_1978" /> This is the name Texas Instruments uses for the input scheme used in some of its calculators.<ref name="TI EOS vs AOS"/>

Immediate-execution calculators are based on a mixture of infix and postfix notation: binary operations are done as infix, but unary operations are postfix. Because operators are applied one-at-a-time, the user must work out which operator key to use at each stage, and this can lead to problems.<ref name="Thimbleby_1998"/><ref name="Holmes_2003"/> 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".<ref name="PhysOrg_2005"/>

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* For the above reasons, the sequence of button presses may bear little resemblance to the original formula.

* The operation carried out when a button is pressed is not always the same as the button, but could be a previously entered operation.

[[File:Calculator-TI-30XA-rev2015.jpg|thumb|upright|This TI-30XA scientific calculator uses immediate execution. It has a one-line, seven-segmented display, and cannot display operands or allow the entries to be edited.]]

===Examples of difficulties===