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<html><title>Programming Ruby: The Pragmatic Programmer's Guide</title><head><meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"><STYLE TYPE="text/css"><!--
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</STYLE><table bgcolor="#a03030" cellpadding="3" border="0" cellspacing="0"><tr><td colspan="3"><table bgcolor="#902020" cellpadding="20"><tr><td><h1 class="header">Programming Ruby</h1><h3 class="subheader">The Pragmatic Programmer's Guide</h3></td></tr></table></td></tr><tr><td width="33%" align="left"><a class="subheader" href="ref_c_fixnum.html">Previous <</a></td><td width="33%" align="center" valign="middle"><a class="subheader" href="builtins.html">Contents ^</a><br></td><td width="33%" align="right"><a class="subheader" href="ref_c_hash.html">Next ></a><br></td></tr></table></head><body bgcolor="white">
<!--
Copyright (c) 2001 by Addison Wesley Longman. 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/).
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<table><tr><td height="20"><img src="dot.gif" width="1" height="20"></td></tr></table><table border="0" width="100%" bgcolor="660066" cellpadding="10"><tr><td valign="center"><font color="white" size="7">class Float</font></td><td><table border="0"><tr><td><font color="white">
Parent:
</font></td><td><font color="white">Numeric</font></td></tr><tr><td><font color="white">
Version:
</font></td><td><font color="white">
1.6
</font></td></tr></table></td></tr></table><p></p><H3>Index:</H3><a href="#Arithmeticoperations"><i>Arithmetic operations</i></a> <a href="#_lt_eq_lt"><i><=></i></a> <a href="#ceil"><i>ceil</i></a> <a href="#finite_qm"><i>finite?</i></a> <a href="#floor"><i>floor</i></a> <a href="#infinite_qm"><i>infinite?</i></a> <a href="#nan_qm"><i>nan?</i></a> <a href="#round"><i>round</i></a> <a href="#to_f"><i>to_f</i></a> <a href="#to_i"><i>to_i</i></a> <a href="#to_s"><i>to_s</i></a> <p></p><hr>
<code>Float</code> objects represent real numbers using the native
architecture's double-precision floating point representation.
<P></P>
<table border="0" width="100%" cellpadding="10"><tr><td valign="center" colspan="2" bgcolor="990066"><font color="white" size="6">instance methods
</font></td></tr><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="Arithmeticoperations"><b>Arithmetic operations</b></a></font></td><td bgcolor="#ffaaaa">
<P></P>
</td></tr><td></td><td>
<P></P>
Performs various arithmetic operations on <i>flt</i>.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3">
<tr>
<td valign="top"><i>flt</i></td>
<td valign="top">+</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Addition</td>
</tr>
<tr>
<td valign="top"><i>flt</i></td>
<td valign="top">--</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Subtraction</td>
</tr>
<tr>
<td valign="top"><i>flt</i></td>
<td valign="top">*</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Multiplication</td>
</tr>
<tr>
<td valign="top"><i>flt</i></td>
<td valign="top">/</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Division</td>
</tr>
<tr>
<td valign="top"><i>flt</i></td>
<td valign="top">%</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Modulo</td>
</tr>
<tr>
<td valign="top"><i>flt</i></td>
<td valign="top">**</td>
<td valign="top"><i>aNumeric</i></td>
<td valign="top">Exponentiation</td>
</tr>
</table>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="_lt_eq_lt"><b><=></b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i> <=> <i>aNumeric</i>
-> -1, 0, +1
</td></tr><td></td><td>
<P></P>
Returns -1, 0, or +1 depending on whether <i>flt</i> is less
than, equal to, or greater than <i>aNumeric</i>. This is the
basis for the tests in <code>Comparable</code>.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="ceil"><b>ceil</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.ceil -> <i>anInteger</i>
</td></tr><td></td><td>
<P></P>
Returns the smallest <code>Integer</code> greater than or equal to <i>flt</i>.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="500">
<tr>
<td valign="top"><code>1.2.ceil</code></td>
<td valign="top"></td>
<td valign="top"><code>2</code></td>
</tr>
<tr>
<td valign="top"><code>2.0.ceil</code></td>
<td valign="top"></td>
<td valign="top"><code>2</code></td>
</tr>
<tr>
<td valign="top"><code>(-1.2).ceil</code></td>
<td valign="top"></td>
<td valign="top"><code>-1</code></td>
</tr>
<tr>
<td valign="top"><code>(-2.0).ceil</code></td>
<td valign="top"></td>
<td valign="top"><code>-2</code></td>
</tr>
</table>
<P></P>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="finite_qm"><b>finite?</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.finite? -> <code>true</code> or <code>false</code>
</td></tr><td></td><td>
<P></P>
Returns <code>true</code> if <i>flt</i> is a valid IEEE floating point
number (it is not infinite, and <code>nan?</code> is <code>false</code>).
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="floor"><b>floor</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.floor -> <i>anInteger</i>
</td></tr><td></td><td>
<P></P>
Returns the largest integer less than or equal to <i>flt</i>.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="500">
<tr>
<td valign="top"><code>1.2.floor</code></td>
<td valign="top"></td>
<td valign="top"><code>1</code></td>
</tr>
<tr>
<td valign="top"><code>2.0.floor</code></td>
<td valign="top"></td>
<td valign="top"><code>2</code></td>
</tr>
<tr>
<td valign="top"><code>(-1.2).floor</code></td>
<td valign="top"></td>
<td valign="top"><code>-2</code></td>
</tr>
<tr>
<td valign="top"><code>(-2.0).floor</code></td>
<td valign="top"></td>
<td valign="top"><code>-2</code></td>
</tr>
</table>
<P></P>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="infinite_qm"><b>infinite?</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.infinite? -> <code>nil</code>, -1,
+1
</td></tr><td></td><td>
<P></P>
Returns <code>nil</code>, -1, or +1 depending on whether <i>flt</i> is finite,
-infinity, or +infinity.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="500">
<tr>
<td valign="top"><code>(0.0).infinite?</code></td>
<td valign="top"></td>
<td valign="top"><code>nil</code></td>
</tr>
<tr>
<td valign="top"><code>(-1.0/0.0).infinite?</code></td>
<td valign="top"></td>
<td valign="top"><code>-1</code></td>
</tr>
<tr>
<td valign="top"><code>(+1.0/0.0).infinite?</code></td>
<td valign="top"></td>
<td valign="top"><code>1</code></td>
</tr>
</table>
<P></P>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="nan_qm"><b>nan?</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.nan? -> <code>true</code> or <code>false</code>
</td></tr><td></td><td>
<P></P>
Returns <code>true</code> if <i>flt</i> is an invalid IEEE
floating point number.
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="500">
<tr>
<td valign="top"><code>a = -1.0</code></td>
<td valign="top"></td>
<td valign="top"><code>-1.0</code></td>
</tr>
<tr>
<td valign="top"><code>a.nan?</code></td>
<td valign="top"></td>
<td valign="top"><code>false</code></td>
</tr>
<tr>
<td valign="top"><code>a = Math.log(a)</code></td>
<td valign="top"></td>
<td valign="top"><code>NaN</code></td>
</tr>
<tr>
<td valign="top"><code>a.nan?</code></td>
<td valign="top"></td>
<td valign="top"><code>true</code></td>
</tr>
</table>
<P></P>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="round"><b>round</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.round -> <i>anInteger</i>
</td></tr><td></td><td>
<P></P>
Rounds <i>flt</i> to the nearest integer. Equivalent to:
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="400"><tr><td><pre>
def round
return floor(self+0.5) if self > 0.0
return ceil(self-0.5) if self < 0.0
return 0.0
end
</pre></td></tr></table>
<P></P>
<table bgcolor="#fff0f0" cellspacing="0" border="0" cellpadding="3" width="500">
<tr>
<td valign="top"><code>1.5.round</code></td>
<td valign="top"></td>
<td valign="top"><code>2</code></td>
</tr>
<tr>
<td valign="top"><code>(-1.5).round</code></td>
<td valign="top"></td>
<td valign="top"><code>-2</code></td>
</tr>
</table>
<P></P>
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="to_f"><b>to_f</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.to_f -> <i>flt</i>
</td></tr><td></td><td>
<P></P>
Returns <i>flt</i>.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="to_i"><b>to_i</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.to_i -> <i>anInteger</i>
</td></tr><td></td><td>
<P></P>
Returns <i>flt</i> truncated to an <code>Integer</code>.
<P></P>
</td><tr><td valign="center" bgcolor="#ff9999"><font size="4"><a name="to_s"><b>to_s</b></a></font></td><td bgcolor="#ffaaaa">
<i>flt</i>.to_s -> <i>aString</i>
</td></tr><td></td><td>
<P></P>
Returns a string containing a representation of self. As well as
a fixed or exponential form of the number, the call may return
``<code>NaN</code>'', ``<code>Infinity</code>'', and ``<code>-Infinity</code>''.
<P></P>
</td></table>
<P></P>
<p></p><hr><table bgcolor="#a03030" cellpadding="10" border="0" cellspacing="0"><tr><td width="33%" align="left"><a class="subheader" href="ref_c_fixnum.html">Previous <</a></td><td width="33%" align="center" valign="middle"><a class="subheader" href="builtins.html">Contents ^</a><br></td><td width="33%" align="right"><a class="subheader" href="ref_c_hash.html">Next ></a><br></td></tr></table><p></p><font size="-1">Extracted from the book "Programming Ruby -
The Pragmatic Programmer's Guide"</font><br><font size="-3">
Copyright
©
2000 Addison Wesley Longman, Inc. Released under the terms of the
<a href="http://www.opencontent.org/openpub/">Open Publication License</a> V1.0.
<br>
This reference is available for
<a href="http://www.pragmaticprogrammer.com/ruby/downloads/book.html">download</a>.
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