名前空間
変種
操作

std::logb

提供: cppreference.com
< cpp‎ | numeric‎ | math

このページは、Google 翻訳を使って英語版から機械翻訳されました。

翻訳には誤りや奇妙な言い回しがあるかもしれません。文章の上にポインタをおくと、元の文章が見れます。誤りを修正して翻訳を改善する手助けをしてください。翻訳についての説明は、ここをクリックしてください。

このページの英語版を見るにはここをクリックしてください

 
C++
 
ニューメリックスライブラリ
一般的な数学関数
浮動小数点環境
複素数
数値配列
擬似乱数生成
コンパイル時有理数演算 (C++11)
汎用の数値演算
Original:
Generic numeric operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
iota(C++11)
accumulate
inner_product
adjacent_difference
partial_sum
 
一般的な数学関数
機能します
Original:
Functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
基本操作
Original:
Basic operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
remainder(C++11)
remquo(C++11)
fma(C++11)
fmax(C++11)
fmin(C++11)
fdim(C++11)
nan
nanf
nanl		(C++11)
(C++11)
(C++11)
指数関数
Original:
Exponential functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
exp
exp2(C++11)
expm1(C++11)
log
log10
log1p(C++11)
log2(C++11)
電源機能
Original:
Power functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
sqrt
cbrt(C++11)
hypot(C++11)
pow
三角関数や双曲線関数
Original:
Trigonometric and hyperbolic functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
sinh
cosh
tanh
asinh(C++11)
acosh(C++11)
atanh(C++11)
エラーおよびガンマ関数
Original:
Error and gamma functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
erf(C++11)
erfc(C++11)
lgamma(C++11)
tgamma(C++11)
最も近い整数の浮動小数点演算
Original:
Nearest integer floating point operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
ceil
floor
round
lround
llround		(C++11)
(C++11)
(C++11)
trunc(C++11)
nearbyint(C++11)
rint
lrint
llrint		(C++11)
(C++11)
(C++11)
点操作関数に浮かぶ
Original:
Floating point manipulation functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
ldexp
scalbn
scalbln		(C++11)
(C++11)
ilogb(C++11)
logb(C++11)
frexp
modf
nextafter
nexttoward		(C++11)
(C++11)
copysign(C++11)
分類/比較
Original:
Classification/Comparison
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
fpclassify(C++11)
isfinite(C++11)
isinf(C++11)
isnan(C++11)
isnormal(C++11)
signbit(C++11)
isgreater(C++11)
isgreaterequal(C++11)
isless(C++11)
islessequal(C++11)
islessgreater(C++11)
isunordered(C++11)
マクロ定数
Original:
Macro constants
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
FP_NORMAL
FP_SUBNORMAL
FP_ZERO
FP_INFINITE
FP_NAN		(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
 
Defined in header <cmath>
float       logb( float arg );
 (C++11およびそれ以降)
double      logb( double arg );
 (C++11およびそれ以降)
long double logb( long double arg );
 (C++11およびそれ以降)
double      logb( Integral arg );
 (C++11およびそれ以降)
浮動小数点引数argから指数の値を抽出し、浮動小数点値として返します。正式には、結果が符号付き浮動小数点値としてlog
r|arg|の不可欠な部分であり、非ゼロの引数のため、どこrですstd::numeic_limits<T>::radixとTargの浮動小数点型である。 argが非正規の場合は、それが標準化したかのように扱われます.
Original:
Extracts the value of the exponent from the floating-point argument arg, and returns it as a floating-point value. Formally, the result is the integral part of log
r|arg| as a signed floating-point value, for non-zero arg, where r is std::numeic_limits<T>::radix and T is the floating-point type of arg. If arg is subnormal, it is treated as though it was normalized.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

目次

[編集] パラメータ

arg -
浮動小数点値
Original:
floating point value
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[編集] 値を返します

浮動小数点の指数.
Original:
The floating-point exponent.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
argがゼロの場合は領域エラーまたは範囲エラーが発生することがあります.
Original:
Domain or range error may occur if arg is zero.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[編集] ノート

std::logbによって返さ指数std::frexpため、e、1〜std::logb（通常|arg*r-e
|間r）、しかしのために：1によって返される指数の値は、常に異なるため、正規化要件の2によって再び調整指数が1未満である指数部がestd::frexpによって返さ|arg*2-e
|です0.5間1.
Original:
The value of the exponent returned by std::logb is always 1 less than the exponent retuned by std::frexp because of the different normalization requirements: for the exponent e returned by std::logb, |arg*r-e
| is between 1 and r (typically between 1 and 2), but for the exponent e returned by std::frexp, |arg*2-e
| is between 0.5 and 1.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[編集] 例

異なる浮動小数点分解機能を比較します
Original:
Compares different floating-point decomposition functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

このコードを実行します
#include <iostream>
#include <cmath>
#include <limits>
int main()
{
    double f = 123.45;
    std::cout << "Given the number " << f << " or " << std::hexfloat
              << f << std::defaultfloat << " in hex,\n";
 
    double f3;
    double f2 = std::modf(f, &f3);
    std::cout << "modf() makes " << f3 << " + " << f2 << '\n';
 
    int i;
    f2 = std::frexp(f, &i);
    std::cout << "frexp() makes " << f2 << " * 2^" << i << '\n';
 
    i = std::ilogb(f);
    std::cout << "logb()/ilogb() make " << f/std::scalbn(1.0, i) << " * "
              << std::numeric_limits<double>::radix
              << "^" << std::ilogb(f) << '\n';
}

出力: 

Given the number 123.45 or 0x1.edccccccccccdp+6 in hex,
modf() makes 123 + 0.45
frexp() makes 0.964453 * 2^7
logb()/ilogb() make 1.92891 * 2^6

[編集] も参照してください
数値は仮数と2の力に分解する
Original:
decomposes a number into significand and a power of 2
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(関数) [edit]
(C++11)
数値の指数を抽出します
Original:
extracts exponent of the number
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(関数) [edit]
(C++11)
(C++11)
累乗しFLT_RADIXによって数を乗算します
Original:
multiplies a number by FLT_RADIX raised to a power
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(関数) [edit]
「http://ja.cppreference.com/mwiki/index.php?title=cpp/numeric/math/logb&oldid=27482」から取得