FE_DOWNWARD, FE_TONEAREST, FE_TOWARDZERO, FE_UPWARD

 

C++

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Espressioni regolari(C++11)

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In fase di compilazione aritmetica razionale(C++11)

Generici operazioni numeriche 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

 

Virgola mobile ambiente

Funzioni 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)

Macro costanti 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)

 

Elemento definito nell'header <cfenv>
#define FE_DOWNWARD     /*implementation defined*/		(dal C++11)
#define FE_TONEAREST    /*implementation defined*/		(dal C++11)
#define FE_TOWARDZERO   /*implementation defined*/		(dal C++11)
#define FE_UPWARD       /*implementation defined*/		(dal C++11)

Ciascuna di queste costanti macro restituisce un negativo espressione intero costante, che può utilizzare con me std::fesetround e std::fegetround per indicare uno dei supportate virgola mobile modalità di arrotondamento. L'applicazione può definire ulteriori costanti modalità di arrotondamento nel <cfenv>, che dovrebbero iniziare con FE_ seguita da almeno una lettera maiuscola. Ogni macro è definito solo se supportato.

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.

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Sulla maggior parte delle implementazioni, queste costanti macro espandere i valori uguali ai valori di FLT_ROUNDS e std::float_round_style

Original:

On most implementations, these macro constants expand to the values equal to the values of FLT_ROUNDS and std::float_round_style

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Constant 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	arrotondamento verso l'infinito negativo 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	arrotondamento verso l'intero più vicino 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	arrotondamento verso lo zero 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	arrotondamento verso l'infinito positivo 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.

Ulteriori modalità di arrotondamento può essere supportato da una implementazione.

Original:

Additional rounding modes may be supported by an implementation.

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Esempio

#include <cmath>#include <cfenv>#include <iostream>   int main(){#pragma STDC FENV_ACCESS ONstd::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

Vedi anche

float_round_style	indica virgola mobile modalità di arrotondamento 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. (enum)
fegetround fesetround (C++11) (C++11)	ottiene o imposta la direzione di arrotondamento 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. (funzione)