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GNU Emacs Lisp Reference Manual

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3. Numbers

GNU Emacs supports two numeric data types: integers and floating point numbers. Integers are whole numbers such as -3, 0, 7, 13, and 511. Their values are exact. Floating point numbers are numbers with fractional parts, such as -4.5, 0.0, or 2.71828. They can also be expressed in exponential notation: 1.5e2 equals 150; in this example, `e2' stands for ten to the second power, and that is multiplied by 1.5. Floating point values are not exact; they have a fixed, limited amount of precision.

3.1 Integer Basics  Representation and range of integers.
3.2 Floating Point Basics  Representation and range of floating point.
3.3 Type Predicates for Numbers  Testing for numbers.
3.4 Comparison of Numbers  Equality and inequality predicates.
3.5 Numeric Conversions  Converting float to integer and vice versa.
3.6 Arithmetic Operations  How to add, subtract, multiply and divide.
3.7 Rounding Operations  Explicitly rounding floating point numbers.
3.8 Bitwise Operations on Integers  Logical and, or, not, shifting.
3.9 Standard Mathematical Functions  Trig, exponential and logarithmic functions.
3.10 Random Numbers  Obtaining random integers, predictable or not.


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  Copyright 2003   by The Free Software Foundation     Updated Jun 2003