Calculator input methods: Difference between revisions

Revision as of 13:45, 4 May 2009

Revision as of 13:47, 4 May 2009

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There are various ways in which the in which a button-operated calculator might interpret key strokes.

=== Reverse Polish Notation (RPN) (Postfix notation) ===

{{main|Reverse Polish Notation}}

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Note example 1 which is one of the few examples where Reverse Polish Notation does not use the fewest button presses - provided one does not rearrange operands. If one would do so then only 5 key strokes would be needed.

=== Immediate execution ===

=== infix notation (without [[order of operations]]) ===

With this mode of operation each [[binary operation]] is executed as soon as the next operator is pressed, therefore the order of operations in a mathematical expression is not taken into account, except for models which have buttons for brackets which can take order in to account. Also for [[unitary operators]] like √ or x² the number is entered first then the operator.

{{main|Infix notation}}

Infix notation without [[order of operations]] is used by simple non-scientific calculators. With this mode the mathematical order of operations is not honored and all operations are immediately executed. Also advanced operations like √ or x² are entered after the operation.

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From the first example one can see that it is necessary to rearrange operands in order to get the correct result.

=== infixInfix notation (with [[order of operations]]) ===

{{main|orderinfix of operationsnotation}}

With this mode the mathematical order of operations is where honored.

Infix notation with [[order of operations]] where used by scientific calculators in from the 70th to the 90th. With this mode the mathematical order of operations is where honored but advanced operations like √ or x² where are still entered after the operation. This mode of operation has been replaced by [[#Direct_algebraic_logic_.28D.A.L..29|Direct algebraic logic]].

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Some BASIC programmable [[Pocket computer|Pocket computers]] had dedicated trigonometric keys <ref>The picture of the [http://pocket.free.fr/html/casio/fx-880p_e.html FX-880P] show sin, cos and tan keys on the second row right hand side.</ref> hence the keystroke count is given as a range. Some BASIC programmable [[Pocket computer|Pocket computers]] could also be operate in arithmetic logic.

This mode of operation to has been replaced by [[#Direct_algebraic_logic_.28D.A.L..29|Direct algebraic logic]].

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=== Mathematical display ===

=== '''Direct algebraic logic (D.A.L.)''' ===

Some calculators allow the entering of equations in a way which resembles how they would normally be written.

===[[Sharp Corporation|SHARP]] calls this method '''Direct algebraic logic (D.A.L.)''' ===.

'''Direct algebraic logic (D.A.L.)''' is a method for entering equations on scientific calculators which allows symbols and numbers to be entered as they are written. [[Sharp Corporation|SHARP]] introduced it in [[1992]]<ref>[http://sharp-world.com/contents/calculator/features/standard/dal D.A.L description] from Sharp</ref>. Today D.A.L. is used almost with every scientific calculator except those which use [[Reverse Polish Notation]].

Casio calls this method '''Visually Perfect Algebraic Mode (V.P.A.M)'''.

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Note the <code>→</code> in the 2nd example: most DALof these calculators will automatically insert needed parenthesis and the <code>→</code> key skips over the closing parenthesis from the sin operation. Machines equipped with an alphanumeric display will

display <tt>SIN(30)×COS(30)</tt> before pressing <code>ENTER</code>.