std::numeric_limits::tinyness_before
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<metanoindex/>
<tbody> </tbody> static const bool tinyness_before |
(bis C + +11) | |
static constexpr bool tinyness_before |
(seit C++11) | |
Der Wert der
std::numeric_limits<T>::has_denorm_loss ist true für alle Floating-Point-Typen T Testergebnisse der Floating-Point-Ausdrücke für Unterlauf vor dem Runden .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.
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Standard Spezialisierungen
T
|
Wert
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
|
Implementierung definiert
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
|
Implementierung definiert
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
|
Implementierung definiert
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
Standard-konformen IEEE 754 Floating-Point-Implementierungen können die Gleitkommaunterlauf an drei vordefinierten Momente erkennen:
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)
nach der Berechnung eines Ergebnisses mit absoluter Wert kleiner als
std::numeric_limits<T>::min(), erkennt diese Umsetzung tinyness vor der Rundung (zB 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)
nach dem Runden des Ergebnisses auf
std::numeric_limits<T>::digits Bits, wenn das Ergebnis kleiner, erkennt diese Umsetzung tinyness nach Rundung (zB 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)
wenn die Umwandlung des abgerundeten winzigen Ergebnis subnormale Form in Folge des Verlusts an Genauigkeit detektiert diese Umsetzung denorm Verlust .
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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Beispiel
Multiplikation des größten subnormale Zahl durch die Anzahl einer Maschine epsilon größer als 1,0 ergibt die winzigen Wert 0x0.fffffffffffff8p-1022 vor der Rundung, aber Normalwert 1p-1022 nach dem Runden .
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';
}
Output:
Inexact result detected
0x0.fffffffffffffp-1022 x 0x1.0000000000001p+0 = 0x1p-1022
Siehe auch
[statisch] |
identifies the floating-point types that detect loss of precision as denormalization loss rather than inexact result (public static Mitglied konstanten) |
[statisch] |
identifiziert die Denormalisierung Stil durch den Floating-Point-Typ verwendet 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. (public static Mitglied konstanten) |