# Programming Ruby ### The Pragmatic Programmer's Guide
Previous < | Contents ^ | Next >

class Float |
Parent: | Numeric
Version: | 1.6

### Index:

Arithmetic operations <=> ceil finite? floor infinite? nan? round to_f to_i to_s

`Float` objects represent real numbers using the native architecture's double-precision floating point representation.

instance methods
Arithmetic operations |
|  | Performs various arithmetic operations on flt.
flt | + | aNumeric | Addition
flt | -- | aNumeric | Subtraction
flt | * | aNumeric | Multiplication
flt | / | aNumeric | Division
flt | % | aNumeric | Modulo
flt | ** | aNumeric | Exponentiation
<=> | flt <=> aNumeric -> -1, 0, +1
|  | Returns -1, 0, or +1 depending on whether flt is less than, equal to, or greater than aNumeric. This is the basis for the tests in `Comparable`.
ceil | flt.ceil -> anInteger
|  | Returns the smallest `Integer` greater than or equal to flt.
`1.2.ceil` | » | `2`
`2.0.ceil` | » | `2`
`(-1.2).ceil` | » | `-1`
`(-2.0).ceil` | » | `-2`
finite? | flt.finite? -> `true` or `false`
|  | Returns `true` if flt is a valid IEEE floating point number (it is not infinite, and `nan?` is `false`).
floor | flt.floor -> anInteger
|  | Returns the largest integer less than or equal to flt.
`1.2.floor` | » | `1`
`2.0.floor` | » | `2`
`(-1.2).floor` | » | `-2`
`(-2.0).floor` | » | `-2`
infinite? | flt.infinite? -> `nil`, -1, +1
|  | Returns `nil`, -1, or +1 depending on whether flt is finite, -infinity, or +infinity.
`(0.0).infinite?` | » | `nil`
`(-1.0/0.0).infinite?` | » | `-1`
`(+1.0/0.0).infinite?` | » | `1`
nan? | flt.nan? -> `true` or `false`
|  | Returns `true` if flt is an invalid IEEE floating point number.
`a = -1.0` | » | `-1.0`
`a.nan?` | » | `false`
`a = Math.log(a)` | » | `NaN`
`a.nan?` | » | `true`
round | flt.round -> anInteger
|  | Rounds flt to the nearest integer. Equivalent to:
    def round
      return floor(self+0.5) if self > 0.0
      return ceil(self-0.5)  if self < 0.0
      return 0.0
    end
`1.5.round` | » | `2`
`(-1.5).round` | » | `-2`
to_f | flt.to_f -> flt
|  | Returns flt.
to_i | flt.to_i -> anInteger
|  | Returns flt truncated to an `Integer`.
to_s | flt.to_s -> aString
|  | Returns a string containing a representation of self. As well as a fixed or exponential form of the number, the call may return ```NaN`'', ```Infinity`'', and ```-Infinity`''.

Previous < | Contents ^ | Next >

Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"
Copyright © 2001 by Addison Wesley Longman, Inc. This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/)).

Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder.

Distribution of the work or derivative of the work in any standard (paper) book form is prohibited unless prior permission is obtained from the copyright holder.