1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
<html lang="en">
<head>
<title>Handling floating point exceptions - GNU Scientific Library -- Reference Manual</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="GNU Scientific Library -- Reference Manual">
<meta name="generator" content="makeinfo 4.8">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="Debugging-Numerical-Programs.html" title="Debugging Numerical Programs">
<link rel="prev" href="Examining-floating-point-registers.html" title="Examining floating point registers">
<link rel="next" href="GCC-warning-options-for-numerical-programs.html" title="GCC warning options for numerical programs">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 The GSL Team.
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 the
Invariant Sections being ``GNU General Public License'' and ``Free Software
Needs Free Documentation'', the Front-Cover text being ``A GNU Manual'',
and with the Back-Cover Text being (a) (see below). A copy of the
license is included in the section entitled ``GNU Free Documentation
License''.
(a) The Back-Cover Text is: ``You have freedom to copy and modify this
GNU Manual, like GNU software.''-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
pre.display { font-family:inherit }
pre.format { font-family:inherit }
pre.smalldisplay { font-family:inherit; font-size:smaller }
pre.smallformat { font-family:inherit; font-size:smaller }
pre.smallexample { font-size:smaller }
pre.smalllisp { font-size:smaller }
span.sc { font-variant:small-caps }
span.roman { font-family:serif; font-weight:normal; }
span.sansserif { font-family:sans-serif; font-weight:normal; }
--></style>
</head>
<body>
<div class="node">
<p>
<a name="Handling-floating-point-exceptions"></a>
Next: <a rel="next" accesskey="n" href="GCC-warning-options-for-numerical-programs.html">GCC warning options for numerical programs</a>,
Previous: <a rel="previous" accesskey="p" href="Examining-floating-point-registers.html">Examining floating point registers</a>,
Up: <a rel="up" accesskey="u" href="Debugging-Numerical-Programs.html">Debugging Numerical Programs</a>
<hr>
</div>
<h3 class="section">A.3 Handling floating point exceptions</h3>
<p>It is possible to stop the program whenever a <code>SIGFPE</code> floating
point exception occurs. This can be useful for finding the cause of an
unexpected infinity or <code>NaN</code>. The current handler settings can be
shown with the command <code>info signal SIGFPE</code>.
<pre class="smallexample"> (gdb) info signal SIGFPE
Signal Stop Print Pass to program Description
SIGFPE Yes Yes Yes Arithmetic exception
</pre>
<p class="noindent">Unless the program uses a signal handler the default setting should be
changed so that SIGFPE is not passed to the program, as this would cause
it to exit. The command <code>handle SIGFPE stop nopass</code> prevents this.
<pre class="smallexample"> (gdb) handle SIGFPE stop nopass
Signal Stop Print Pass to program Description
SIGFPE Yes Yes No Arithmetic exception
</pre>
<p class="noindent">Depending on the platform it may be necessary to instruct the kernel to
generate signals for floating point exceptions. For programs using GSL
this can be achieved using the <code>GSL_IEEE_MODE</code> environment variable
in conjunction with the function <code>gsl_ieee_env_setup</code> as described
in see <a href="IEEE-floating_002dpoint-arithmetic.html">IEEE floating-point arithmetic</a>.
<pre class="example"> (gdb) set env GSL_IEEE_MODE=double-precision
</pre>
<hr>The GNU Scientific Library - a free numerical library licensed under the GNU GPL<br>Back to the <a href="/software/gsl/">GNU Scientific Library Homepage</a></body></html>
|
