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Calculator input methods: comparison of notations as used by pocket calculators; Postfix notation, also called Reverse Polish notation; Prefix notation, also called Polish notation; Shunting yard algorithm, used to convert infix notation to postfix notation or to a tree; Operator (computer programming) Subject–verb–object word order
The concept was introduced in the B programming language circa 1969 by Ken Thompson. [16] Thompson went a step further by inventing the ++ and -- operators, which increment or decrement; their prefix or postfix position determines whether the alteration occurs before or after noting the value of the operand.
An operator which is non-associative cannot compete for operands with operators of equal precedence. In Prolog for example, the infix operator :-is non-associative, so constructs such as a :- b :- c are syntax errors. Unary prefix operators such as − (negation) or sin (trigonometric function) are typically associative prefix operators.
The result for the above examples would be (in reverse Polish notation) "3 4 +" and "3 4 2 1 − × +", respectively. The shunting yard algorithm will correctly parse all valid infix expressions, but does not reject all invalid expressions. For example, "1 2 +" is not a valid infix expression, but would be parsed as "1 + 2". The algorithm can ...
Video: Keys pressed for calculating eight times six on a HP-32SII (employing RPN) from 1991. Reverse Polish notation (RPN), also known as reverse Łukasiewicz notation, Polish postfix notation or simply postfix notation, is a mathematical notation in which operators follow their operands, in contrast to prefix or Polish notation (PN), in which operators precede their operands.
This calculator program has accepted input in infix notation, and returned the answer , ¯. Here the comma is a decimal separator. Here the comma is a decimal separator. 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.
Most stack-oriented languages operate in postfix or Reverse Polish notation: arguments or parameters for a command are listed before that command. For example, postfix notation would be written 2, 3, multiply instead of multiply, 2, 3 (prefix or Polish notation), or 2 multiply 3 (infix notation).
dc (desk calculator) is a cross-platform reverse-Polish calculator which supports arbitrary-precision arithmetic. [1] It was written by Lorinda Cherry and Robert Morris at Bell Labs. [2] It is one of the oldest Unix utilities, preceding even the invention of the C programming language. Like other utilities of that vintage, it has a powerful set ...