std::numeric_limits::tinyness_before
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<metanoindex/>
<tbody> </tbody> static const bool tinyness_before |
(avant C++11) | |
static constexpr bool tinyness_before |
(depuis C++11) | |
La valeur de
std::numeric_limits<T>::has_denorm_loss est true pour tous les types à virgule flottante T que les résultats des tests de virgule flottante expressions de débordement avant arrondissement .Original:
The value of
std::numeric_limits<T>::has_denorm_loss is true for all floating-point types T that test results of floating-point expressions for underflow before rounding.The text has been machine-translated via Google Translate.
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Spécialisations standard
T
|
valeur de
std::numeric_limits<T>::tinyness_before Original: value of std::numeric_limits<T>::tinyness_before The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
| /* non-specialized */ | false
|
bool
|
false
|
char
|
false
|
signed char
|
false
|
unsigned char
|
false
|
wchar_t
|
false
|
char16_t
|
false
|
char32_t
|
false
|
short
|
false
|
unsigned short
|
false
|
int
|
false
|
unsigned int
|
false
|
long
|
false
|
unsigned long
|
false
|
long long
|
false
|
unsigned long long
|
false
|
float
|
défini par l'implémentation
Original: implementation-defined The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
double
|
défini par l'implémentation
Original: implementation-defined The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
long double
|
défini par l'implémentation
Original: implementation-defined The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Notes
Conformes à la norme IEEE 754 en virgule flottante implémentations peuvent détecter le dépassement inférieur à virgule flottante à trois moments prédéfinis:
Original:
Standard-compliant IEEE 754 floating-point implementations may detect the floating-point underflow at three predefined moments:
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1)
après calcul d'un résultat à la valeur absolue plus petite que
std::numeric_limits<T>::min(), cette mise en oeuvre détecte tinyness avant arrondi (par exemple UltraSparc)Original:
after computation of a result with absolute value smaller than
std::numeric_limits<T>::min(), such implementation detects tinyness before rounding (e.g. UltraSparc)The text has been machine-translated via Google Translate.
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2)
après arrondi du résultat de bits de
std::numeric_limits<T>::digits, si le résultat est minuscule, cette mise en œuvre détecte tinyness après arrondi (p. ex SPARC)Original:
after rounding of the result to
std::numeric_limits<T>::digits bits, if the result is tiny, such implementation detects tinyness after rounding (e.g. SuperSparc)The text has been machine-translated via Google Translate.
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3)
si la conversion du résultat arrondi à la forme minuscule inférieure à la normale ont entraîné la perte de précision, cette mise en œuvre détecte une perte denorm .
Original:
if the conversion of the rounded tiny result to subnormal form resulted in the loss of precision, such implementation detects denorm loss.
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Exemple
La multiplication du plus grand nombre inférieur à la normale par l'epsilon machine de numéro un supérieur à 1,0 donne la valeur minuscule 0x0.fffffffffffff8p-1022 avant d'arrondir, mais la valeur normale 1p-1022 après avoir contourné .
Original:
Multiplication of the largest subnormal number by the number one machine epsilon greater than 1.0 gives the tiny value 0x0.fffffffffffff8p-1022 before rounding, but normal value 1p-1022 after rounding.
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#include <iostream>
#include <limits>
#include <cmath>
#include <cfenv>
int main()
{
double denorm_max = std::nextafter(std::numeric_limits<double>::min(), 0);
double multiplier = 1 + std::numeric_limits<double>::epsilon();
std::feclearexcept(FE_ALL_EXCEPT);
double result = denorm_max*multiplier; // Underflow only if tinyness_before
if(std::fetestexcept(FE_UNDERFLOW))
std::cout << "Underflow detected\n";
else if (std::fetestexcept(FE_INEXACT))
std::cout << "Inexact result detected\n";
std::cout << std::hexfloat << denorm_max << " x " << multiplier << " = "
<< result << '\n';
}
Résultat :
Inexact result detected
0x0.fffffffffffffp-1022 x 0x1.0000000000001p+0 = 0x1p-1022
Voir aussi
[ statique ]Original: static The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
identifie les types à virgule flottante qui détectent une perte de précision que la perte de dénormalisation plutôt que des résultats inexacts Original: identifies the floating-point types that detect loss of precision as denormalization loss rather than inexact result The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (constante membre statique publique) |
[ statique ]Original: static The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
identifie le style utilisé par la dénormalisation du type à virgule flottante Original: identifies the denormalization style used by the floating-point type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (constante membre statique publique) |