You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
100 lines
4.5 KiB
HTML
100 lines
4.5 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
|
<html>
|
|
<!-- This manual documents how to install and use the Multiple Precision
|
|
Floating-Point Reliable Library, version 3.1.4.
|
|
|
|
Copyright 1991, 1993-2016 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to copy, distribute and/or modify this document under
|
|
the terms of the GNU Free Documentation License, Version 1.2 or any later
|
|
version published by the Free Software Foundation; with no Invariant Sections,
|
|
with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the
|
|
license is included in GNU Free Documentation License. -->
|
|
<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
|
|
<head>
|
|
<title>MPFR Variable Conventions (GNU MPFR 3.1.4)</title>
|
|
|
|
<meta name="description" content="How to install and use GNU MPFR, a library for reliable multiple precision
|
|
floating-point arithmetic, version 3.1.4.">
|
|
<meta name="keywords" content="MPFR Variable Conventions (GNU MPFR 3.1.4)">
|
|
<meta name="resource-type" content="document">
|
|
<meta name="distribution" content="global">
|
|
<meta name="Generator" content="makeinfo">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
|
|
<link href="index.html#Top" rel="start" title="Top">
|
|
<link href="Concept-Index.html#Concept-Index" rel="index" title="Concept Index">
|
|
<link href="MPFR-Basics.html#MPFR-Basics" rel="up" title="MPFR Basics">
|
|
<link href="Rounding-Modes.html#Rounding-Modes" rel="next" title="Rounding Modes">
|
|
<link href="Nomenclature-and-Types.html#Nomenclature-and-Types" rel="prev" title="Nomenclature and Types">
|
|
<style type="text/css">
|
|
<!--
|
|
a.summary-letter {text-decoration: none}
|
|
blockquote.indentedblock {margin-right: 0em}
|
|
blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
|
|
blockquote.smallquotation {font-size: smaller}
|
|
div.display {margin-left: 3.2em}
|
|
div.example {margin-left: 3.2em}
|
|
div.lisp {margin-left: 3.2em}
|
|
div.smalldisplay {margin-left: 3.2em}
|
|
div.smallexample {margin-left: 3.2em}
|
|
div.smalllisp {margin-left: 3.2em}
|
|
kbd {font-style: oblique}
|
|
pre.display {font-family: inherit}
|
|
pre.format {font-family: inherit}
|
|
pre.menu-comment {font-family: serif}
|
|
pre.menu-preformatted {font-family: serif}
|
|
pre.smalldisplay {font-family: inherit; font-size: smaller}
|
|
pre.smallexample {font-size: smaller}
|
|
pre.smallformat {font-family: inherit; font-size: smaller}
|
|
pre.smalllisp {font-size: smaller}
|
|
span.nolinebreak {white-space: nowrap}
|
|
span.roman {font-family: initial; font-weight: normal}
|
|
span.sansserif {font-family: sans-serif; font-weight: normal}
|
|
ul.no-bullet {list-style: none}
|
|
-->
|
|
</style>
|
|
|
|
|
|
</head>
|
|
|
|
<body lang="en">
|
|
<a name="MPFR-Variable-Conventions"></a>
|
|
<div class="header">
|
|
<p>
|
|
Next: <a href="Rounding-Modes.html#Rounding-Modes" accesskey="n" rel="next">Rounding Modes</a>, Previous: <a href="Nomenclature-and-Types.html#Nomenclature-and-Types" accesskey="p" rel="prev">Nomenclature and Types</a>, Up: <a href="MPFR-Basics.html#MPFR-Basics" accesskey="u" rel="up">MPFR Basics</a> [<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
|
|
</div>
|
|
<hr>
|
|
<a name="MPFR-Variable-Conventions-1"></a>
|
|
<h3 class="section">4.3 MPFR Variable Conventions</h3>
|
|
|
|
<p>Before you can assign to an MPFR variable, you need to initialize it by calling
|
|
one of the special initialization functions. When you’re done with a
|
|
variable, you need to clear it out, using one of the functions for that
|
|
purpose.
|
|
A variable should only be initialized once, or at least cleared out between
|
|
each initialization. After a variable has been initialized, it may be
|
|
assigned to any number of times.
|
|
For efficiency reasons, avoid to initialize and clear out a variable in loops.
|
|
Instead, initialize it before entering the loop, and clear it out after the
|
|
loop has exited.
|
|
You do not need to be concerned about allocating additional space for MPFR
|
|
variables, since any variable has a significand of fixed size.
|
|
Hence unless you change its precision, or clear and reinitialize it,
|
|
a floating-point variable will have the same allocated space during all its
|
|
life.
|
|
</p>
|
|
<p>As a general rule, all MPFR functions expect output arguments before input
|
|
arguments. This notation is based on an analogy with the assignment operator.
|
|
MPFR allows you to use the same variable for both input and output in the same
|
|
expression. For example, the main function for floating-point multiplication,
|
|
<code>mpfr_mul</code>, can be used like this: <code>mpfr_mul (x, x, x, rnd)</code>.
|
|
This
|
|
computes the square of <var>x</var> with rounding mode <code>rnd</code>
|
|
and puts the result back in <var>x</var>.
|
|
</p>
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|