.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
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.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
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.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Japanese Version Copyright (c) 2008  Akihiro MOTOKI
.\"         all rights reserved.
.\" Translated 2008-08-17, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v3.07
.\" 
.\"WORD:	significand	
.\"WORD:	domain error	ΰ襨顼
.\"WORD:	pole error	˥顼
.\"WORD:	range error	ϰϥ顼
.\" 
.TH MATH_ERROR 7 2008-08-11 "Linux" "Linux Programmer's Manual"
.SH ̾
math_error \- شؿΥ顼θ
.SH 
.nf
.B #include <math.h>
.B #include <errno.h>
.B #include <fenv.h>
.fi
.SH 
顼ȯȡۤȤɤΥ饤֥ؿ (\-1  NULL ʤɤ)
̤֤ͤȤǥ顼Τ롣
.I <math.h>
Ƥشؿϡ̾ư֤ͤΤǡ
¾εȤäƥ顼Τ롣
顼ε 2 ढꡢ
ŤΤ
.I errno
ꤹǤꡢΤ
.BR fenv (3)
Ƥư㳰Ǥ롣
.RB ( feclearexcept (3)

.BR fetestexcept (3)
Ѥ롣ˤĤƤϰʲdzפƤ롣)

ܿɬפʥץǡشؿΥ顼ǧɬפˤϡ
شؿƤӽФ
.I errno
 0 ꤷʲƤӽФ٤Ǥ롣
.in +4n
.nf

feclearexcept(FE_ALL_EXCEPT);
.fi
.in

شؿ֤äƤݤˡ
.I errno
 0 ʳʲθƤӽФ 0 ʳ֤
.RB ( fenv (3)
)شؿǥ顼ȯƤ롣
.in +4n
.nf

fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |
             FE_UNDERFLOW);
.fi
.in
.\" enum
.\" {
.\" FE_INVALID = 0x01,
.\" __FE_DENORM = 0x02,
.\" FE_DIVBYZERO = 0x04,
.\" FE_OVERFLOW = 0x08,
.\" FE_UNDERFLOW = 0x10,
.\" FE_INEXACT = 0x20
.\" };

شؿȯ륨顼ˤĤƤϰʲ롣
.SS ΰ襨顼 (domain error)
.I ΰ襨顼
ȯΤϡشؿϤ줿ͤδؿƤ
ΰäƤʤǤ (㤨
.BR log (3)
ΰϤ)
ΰ襨顼ȯȡ
شؿ̤ NaN ֤
(Ʊǰ㤦֤ͤؿ⤢)
.I errno

.B EDOM
ꤷ̵ (invalid)
ư㳰
.RB ( FE_INVALID )
夲롣
.SS ˥顼 (pole error)
.I ˥顼
ȯΤϡؿοŪʷ̵̤礽ΤΤȤʤǤ
(㤨
0 п̵Ǥ)
˥顼ȯȡδؿ֤ͤ (դ)
.BR HUGE_VAL ,
.BR HUGE_VALF ,
.B HUGE_VALL
Τ줫Ȥʤ (ͤΤɤ줬֤뤫ϴؿ֤ͤηˤޤꡢ
줾
.IR double ,
.IR float ,
.I "long double"
б)
̤ϡδؿοŪꤵ롣
.I errno

.B ERANGE
ꤵ졢0 ˤ (divide-by-zero)
ư㳰
.RB ( FE_DIVBYZERO )
夬롣
.SS ϰϥ顼 (range 顼)
.I ϰϥ顼
ȯΤϡؿη̤ͤδؿ֤ͤηǤɽǤʤ
Ǥ롣ؿ֤ͤϡϰϥ顼СեǤäե
Ǥäˤäưۤʤ롣

ưΥСեϡ̤ͭ¤礭᤮
̤֤ǤɽǤʤȯ롣
Сեȯȡ
δؿ
.BR HUGE_VAL ,
.BR HUGE_VALF ,
.B HUGE_VALL
Τ줫֤ (ͤΤɤ줬֤뤫ϴؿ֤ͤηˤޤꡢ
줾
.IR double ,
.IR float ,
.I "long double"
б)
.I errno

.B ERANGE
ꤵ졢֥Сե (overflow)
ư㳰
.RB ( FE_OVERFLOW )
夬롣

ưΥեϡ
̤᤮ơ̤֤ǤɽǤʤȯ롣
եȯȡشؿ̾ 0.0 ֤
(C99 Ǥϡꤵ줿ˤƺǾ줿ͤ礭ʤ
ͤļ (implementation-defined) ֤ͤȤʤäƤ)
.I errno

.B ERANGE
ꤵ졢֥եư㳰
.RB ( FE_UNDERFLOW )
夬롣

ĤδؿǤϡϤ줿ͤ䡢ؿη̤
.I subnormal ()
ˤʤϰϥ顼夲롣
subnormal ͤȤϡ0 ǤϤʤͤ
(κǾ̥ӥåȤ 1 Ȥʤ) ɸǤɽǤʤ褦ͤǤ롣
subnormal ͤɽǤϡξ¦ΥӥåȤ 1 İʾ 0 
ޤޤ뤳Ȥˤʤ롣
.SH 
C99  POSIX.1-2001 ǵꤵƤ
.I math_errhandling
̻Ҥ glibc ǤϥݡȤƤʤ
.\" See CONFORMANCE in the glibc 2.8 (and earlier) source.
μ̻Ҥϡ2 ĤΥ顼ε
.RI ( errno

.BR fetestexcept (3)
ͳǼǤ㳰) Τɤ餬ѤƤ뤫
뤳ȤˤʤäƤ롣
ɸǤϡʤȤĤϻѤ뤳Ȥ׵ᤵƤ뤬
ξȤѲǽǤäƤ褤ȤƤ롣
glibc Ǥθߤ (С 2.8 Ǥ) Ϥʤ꺮𤷤Ƥ롣
ۤȤɤδؿ (ǤϤʤ) ϥ顼㳰夲롣
Ĥδؿ
.I errno
ꤹ롣
.I errno
ꤹ뤬㳰夲ʤؿ⾯¸ߤ롣
ɤԤʤؿ⤴¸ߤ롣
ܺ٤ˤĤƤϸġΥޥ˥奢ڡ򻲾ȤΤȡ

.I errno

.BR fetestexcept (3)
ξȤäƥ顼åԤȤʣˤʤΤ򤱤뤿ᡢ
¿ξ硢ؿƤӽФԤʰΥåԤ
ˡ侩Ƥ롣
.\" http://www.securecoding.cert.org/confluence/display/seccode/FLP32-C.+Prevent+or+detect+domain+and+range+errors+in+math+functions
㤨СʲΥɤϡ
.BR log (3)
ΰ NaN Ǥ (˥顼Ȥʤ) 0 Ǥ (ΰ襨顼Ȥʤ) 0 ̤
ǤʤȤݾڤΤǤ롣
.in +4n
.nf

double x, r;

if (isnan(x) || islessequal(x, 0)) {
    /* Deal with NaN / pole error / domain error */
}

r = log(x);

.fi
.in
Υڡ˽񤫤Ƥ뤳Ȥϡ
.RI ( <complex.h>
Ƥ) ʣǿؿˤϤƤϤޤʤ
̤ˡC99  POSIX.1-2001 ǤϤδؿ顼֤Ȥ
׵ᤷƤʤ

.BR gcc (1)

.I "-fno-math-errno"
ץȤȡ¹ԥեǡɸμ®ʿشؿ
Ѥ褦ˤʤ뤬
顼
.I errno
ꤵʤ
.RB ( gcc (1)

.I "-ffast-math"
ץꤷˤ
.I "-fno-math-errno"
ͭˤʤ)
ΥץꤷǤ⡢
.BR fetestexcept (3)
Ȥä顼θϲǽǤ롣
.SH Ϣ
.BR gcc (1),
.BR errno (3),
.BR fenv (3),
.BR fpclassify (3),
.BR INFINITY (3),
.BR isgreater (3),
.BR matherr (3),
.BR nan (3)
.br
.I "info libc"