Reverse Polish notation

Reverse Polish notation (RPN) , also known as postfix notation, is an arithmetic formula notation, derived from the Polish notation introduced in 1920 by the Polish mathematician Jan ?ukasiewicz. RPN was invented by Australian philosopher and computer scientist Charles Hamblin in the mid-1950s, to enable zero-address memory stores.

Related Topics:
Polish notation - 1920 - Polish - Jan ?ukasiewicz - Australia - Charles Hamblin - 1950s

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As a user interface for calculation the notation was first used in Hewlett-Packard's desktop calculators from the late 1960s and then in the HP-35 handheld scientific calculator launched in 1972. In RPN the operands precede the operator, thus dispensing with the need for parentheses. For example, the expression 3 * ( 4 + 7) would be written as 3 4 7 + *, and done on an RPN calculator as "3", "Enter", "4", "Enter", "7", "+", "*". (Alternatively, and more-compactly, it could also be re-ordered and written as 4 7 + 3 *, and done on an RPN calculator as "4", "Enter", "7", "+", "3", "*".)

Related Topics:
Hewlett-Packard - 1960s - HP-35 - Calculator - 1972 - Operand - Operator

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Implementations of RPN are stack-based; that is, operands are popped from a stack, and calculation results are pushed back onto it. Although this concept may seem obscure at first, RPN has the advantage of being extremely easy, and therefore fast, for a computer to analyze.

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