system.3: wfix

[thirdparty/man-pages.git] / man3 / fenv.3

.\" Copyright (c) 2000 Andries Brouwer (aeb@cwi.nl)
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.\" 2000-08-14 added GNU additions from Andreas Jaeger
.\" 2000-12-05 some changes inspired by acahalan's remarks
.\"
.TH FENV 3  2017-09-15 "Linux" "Linux Programmer's Manual"
.SH NAME
feclearexcept, fegetexceptflag, feraiseexcept, fesetexceptflag,
fetestexcept, fegetenv, fegetround, feholdexcept, fesetround,
fesetenv, feupdateenv, feenableexcept, fedisableexcept,
fegetexcept \- floating-point rounding and exception handling
.SH SYNOPSIS
.nf
.B #include <fenv.h>
.PP
.BI "int feclearexcept(int " excepts );
.BI "int fegetexceptflag(fexcept_t *" flagp ", int " excepts );
.BI "int feraiseexcept(int " excepts );
.BI "int fesetexceptflag(const fexcept_t *" flagp ", int " excepts );
.BI "int fetestexcept(int " excepts );
.PP
.B "int fegetround(void);"
.BI "int fesetround(int " rounding_mode );
.PP
.BI "int fegetenv(fenv_t *" envp );
.BI "int feholdexcept(fenv_t *" envp );
.BI "int fesetenv(const fenv_t *" envp );
.BI "int feupdateenv(const fenv_t *" envp );
.fi
.PP
Link with \fI\-lm\fP.
.SH DESCRIPTION
These eleven functions were defined in C99, and describe the handling
of floating-point rounding and exceptions (overflow, zero-divide, etc.).
.SS Exceptions
The
.I divide-by-zero
exception occurs when an operation on finite numbers
produces infinity as exact answer.
.PP
The
.I overflow
exception occurs when a result has to be represented as a
floating-point number, but has (much) larger absolute value than the
largest (finite) floating-point number that is representable.
.PP
The
.I underflow
exception occurs when a result has to be represented as a
floating-point number, but has smaller absolute value than the smallest
positive normalized floating-point number (and would lose much accuracy
when represented as a denormalized number).
.PP
The
.I inexact
exception occurs when the rounded result of an operation
is not equal to the infinite precision result.