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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''.

Extracted from the book "Programming Ruby - The Pragmatic Programmer's Guide"
Copyright © 2000 Addison Wesley Longman, Inc. Released under the terms of the Open Publication License V1.0.
This reference is available for download.