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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 an exponential notation as well: thus, 1.5e2 equals 150;
in this example, `e2' stands for ten to the second power, and is
multiplied by 1.5. Floating point values are not exact; they have a
fixed, limited amount of precision.
Support for floating point numbers is a new feature in Emacs 19, and
it is controlled by a separate compilation option, so you may encounter
a site where Emacs does not support them.
- Integer Basics
- Representation and range of integers.
- Float Basics
- Representation and range of floating point.
- Predicates on Numbers
- Testing for numbers.
- Comparison of Numbers
- Equality and inequality predicates.
- Numeric Conversions
- Converting float to integer and vice versa.
- Arithmetic Operations
- How to add, subtract, multiply and divide.
- Bitwise Operations
- Logical and, or, not, shifting.
- Transcendental Functions
- Trig, exponential and logarithmic functions.
- Random Numbers
- Obtaining random integers, predictable or not.
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