std::numeric_limits::tinyness_before
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<metanoindex/>
<tbody> </tbody> static const bool tinyness_before |
(fino al c++11) | |
static constexpr bool tinyness_before |
(dal C++11) | |
Il valore di
std::numeric_limits<T>::has_denorm_loss è true per tutti i tipi a virgola mobile T che i risultati dei test di virgola mobile espressioni per underflow prima arrotondamento.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.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Specializzazioni standard
T
|
valore di
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
|
implementazione definita
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
|
implementazione definita
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
|
implementazione definita
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. |
Note
Standard-compliant IEEE 754 in virgola mobile implementazioni può rilevare in virgola mobile underflow in tre momenti predefiniti:
Original:
Standard-compliant IEEE 754 floating-point implementations may detect the floating-point underflow at three predefined moments:
The text has been machine-translated via Google Translate.
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1)
dopo il calcolo di un risultato di valore assoluto inferiore a
std::numeric_limits<T>::min(), tale attuazione rileva tinyness prima di arrotondare (ad es 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)
dopo l'arrotondamento del risultato a pezzi
std::numeric_limits<T>::digits, se il risultato è molto piccolo, tale attuazione rileva tinyness dopo l'arrotondamento (per esempio SuperSPARC)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)
se la conversione del risultato arrotondato minuscolo a forma subnormal provocato la perdita di precisione, tale attuazione rileva la perdita denorm.
Original:
if the conversion of the rounded tiny result to subnormal form resulted in the loss of precision, such implementation detects denorm loss.
The text has been machine-translated via Google Translate.
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Esempio
Moltiplicazione del maggior numero subnormale dal numero epsilon una macchina superiore a 1,0 indica il valore del piccolo 0x0.fffffffffffff8p-1022 prima di arrotondare, ma il valore normale 1p-1022 dopo l'arrotondamento .
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.
The text has been machine-translated via Google Translate.
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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';
}
Output:
Inexact result detected
0x0.fffffffffffffp-1022 x 0x1.0000000000001p+0 = 0x1p-1022
Vedi anche
[statico] |
identifies the floating-point types that detect loss of precision as denormalization loss rather than inexact result (pubblico membro statico costante) |
[statico] |
identifica lo stile denormalizzazione utilizzato dal tipo a virgola mobile 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. (pubblico membro statico costante) |