名前空間
変種
操作

FE_DOWNWARD, FE_TONEAREST, FE_TOWARDZERO, FE_UPWARD

提供: cppreference.com
< cpp‎ | numeric‎ | fenv

 
 
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
 
浮動小数点環境
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.
feclearexcept(C++11)
fetestexcept(C++11)
feraiseexcept(C++11)
fegetexceptflag
fesetexceptflag
(C++11)
(C++11)
fegetround
fesetround
(C++11)
(C++11)
fegetenv
fesetenv
(C++11)
feholdexcept(C++11)
feupdateenv(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.
FE_ALL_EXCEPT
FE_DIVBYZERO
FE_INEXACT
FE_INVALID
FE_OVERFLOW
FE_UNDERFLOW
(C++11)
FE_DOWNWARD
FE_TONEAREST
FE_TOWARDZERO
FE_UPWARD
(C++11)
FE_DFL_ENV(C++11)
 
Defined in header <cfenv>
#define FE_DOWNWARD     /*implementation defined*/
(C + + 11以来)
#define FE_TONEAREST    /*implementation defined*/
(C + + 11以来)
#define FE_TOWARDZERO   /*implementation defined*/
(C + + 11以来)
#define FE_UPWARD       /*implementation defined*/
(C + + 11以来)
これらのマクロ定数はそれぞれ、とstd::fesetroundサポートする浮動小数点丸めモードのいずれかを示すために、私はstd::fegetroundで使用することができます非負整数定数式に展開されます。実装は<cfenv>が少なくともひとつの大文字が続くとすべて始めるべきFE_で追加丸めモード定数を定義することができます。それがサポートされている場合、それぞれのマクロは、定義されています.
Original:
Each of these macro constants expands to a nonnegative integer constant expression, which can me used with std::fesetround and std::fegetround to indicate one of the supported floating-point rounding modes. The implementation may define additional rounding mode constants in <cfenv>, which should all begin with FE_ followed by at least one uppercase letter. Each macro is only defined if it is supported.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
ほとんどの実装では、これらのマクロ定数はFLT_ROUNDSstd::float_round_styleの値に等しい値に展開します
Original:
On most implementations, these macro constants expand to the values equal to the values of FLT_ROUNDS and std::float_round_style
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
定数
Original:
Constant
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Explanation
FE_DOWNWARD
負の無限大に向かって丸め
Original:
rounding towards negative infinity
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
FE_TONEAREST
最も近い整数に向かって丸め
Original:
rounding towards nearest integer
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
FE_TOWARDZERO
ゼロ方向に丸め
Original:
rounding towards zero
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
FE_UPWARD
正の無限大に向かって丸め
Original:
rounding towards positive infinity
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
追加の丸めモードが実装によってサポートされるかもしれません.
Original:
Additional rounding modes may be supported by an implementation.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[編集]

[edit]
#include <cmath>
#include <cfenv>
#include <iostream>
 
int main()
{
    #pragma STDC FENV_ACCESS ON
    std::fesetround(FE_DOWNWARD);
    std::cout << "rounding using FE_DOWNWARD: \n" << std::fixed
              << " 12.0 ->  " << std::nearbyint(12.0) << '\n'
              << " 12.1 ->  " << std::nearbyint(12.1) << '\n'
              << "-12.1 -> " << std::nearbyint(-12.1) << '\n'
              << " 12.5 ->  " << std::nearbyint(12.5) << '\n'
              << " 12.9 ->  " << std::nearbyint(12.9) << '\n'
              << "-12.9 -> " << std::nearbyint(-12.9) << '\n'
              << " 13.0 ->  " << std::nearbyint(13.0) << '\n';
    std::fesetround(FE_TONEAREST);
    std::cout << "rounding using FE_TONEAREST: \n"
              << " 12.0 ->  " << std::nearbyint(12.0) << '\n'
              << " 12.1 ->  " << std::nearbyint(12.1) << '\n'
              << "-12.1 -> " << std::nearbyint(-12.1) << '\n'
              << " 12.5 ->  " << std::nearbyint(12.5) << '\n'
              << " 12.9 ->  " << std::nearbyint(12.9) << '\n'
              << "-12.9 -> " << std::nearbyint(-12.9) << '\n'
              << " 13.0 ->  " << std::nearbyint(13.0) << '\n';
}

Output:

rounding using FE_DOWNWARD:
 12.0 ->  12.000000
 12.1 ->  12.000000
-12.1 -> -13.000000
 12.5 ->  12.000000
 12.9 ->  12.000000
-12.9 -> -13.000000
 13.0 ->  13.000000
rounding using FE_TONEAREST: 
 12.0 ->  12.000000
 12.1 ->  12.000000
-12.1 -> -12.000000
 12.5 ->  12.000000
 12.9 ->  13.000000
-12.9 -> -13.000000
 13.0 ->  13.000000

[編集] も参照してください

浮動小数点丸めモードを示しています
Original:
indicates floating-point rounding modes
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(列挙) [edit]
(C++11)
(C++11)
丸め方向を取得または設定します
Original:
gets or sets rounding direction
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(機能) [edit]