Topic summary
Algebraic Operating System
Extracted from the Wikipedia article Calculator input methods.
Immediate execution
The 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 calculators, where operator precedence is observed. Different forms of operator precedence schemes exist. In the algebraic entry system with hierarchy (AESH), the precedence of basic mathematical operators is taken into account, whereas calculators with algebraic entry system with parentheses (AESP) support the entry of parentheses. An input scheme known as algebraic operating system (AOS) combines both. This is the name Texas Instruments uses for the input scheme used in some of its calculators.
