Next: Strings and Characters, Previous: Lisp Data Types, Up: Top [Contents][Index]

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.
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. |