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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. Floating-point numbers are numbers with fractional parts, such as -4.5, 0.0, and 2.71828. They can also be expressed in exponential notation: ‘1.5e2’ is the same as ‘150.0’; here, ‘e2’ stands for ten to the second power, and that is multiplied by 1.5. Integer computations are exact, though they may overflow. Floating-point computations often involve rounding errors, as the numbers have a fixed amount of precision.
| • 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. | |
| • Rounding Operations: | Explicitly rounding floating-point numbers. | |
| • Bitwise Operations: | Logical and, or, not, shifting. | |
| • Math Functions: | Trig, exponential and logarithmic functions. | |
| • Random Numbers: | Obtaining random integers, predictable or not. |