Espaços nominais
Variantes
Acções

std::ilogb

Da cppreference.com
< cpp‎ | numeric‎ | math

 
 
Biblioteca numéricos
Funções matemáticas comuns
De ponto flutuante ambiente
Números complexos
Matrizes numéricas
Pseudo-aleatório de geração de números
Tempo de compilação aritmética racional (C++11)
Genéricos operações numéricas
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
 
Funções matemáticas comuns
Funções
Original:
Functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Operações básicas
Original:
Basic operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
remainder(C++11)
remquo(C++11)
fma(C++11)
fmax(C++11)
fmin(C++11)
fdim(C++11)
nan
nanf
nanl
(C++11)
(C++11)
(C++11)
Funções exponenciais
Original:
Exponential functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
exp
exp2(C++11)
expm1(C++11)
log
log10
log1p(C++11)
log2(C++11)
Funções de poder
Original:
Power functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
sqrt
cbrt(C++11)
hypot(C++11)
pow
Funções trigonométricas e hiperbólicas
Original:
Trigonometric and hyperbolic functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
sinh
cosh
tanh
asinh(C++11)
acosh(C++11)
atanh(C++11)
Erro e funções gamma
Original:
Error and gamma functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
erf(C++11)
erfc(C++11)
lgamma(C++11)
tgamma(C++11)
Número inteiro mais próximo de operações de ponto flutuante
Original:
Nearest integer floating point operations
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
ceil
floor
round
lround
llround
(C++11)
(C++11)
(C++11)
trunc(C++11)
nearbyint(C++11)
rint
lrint
llrint
(C++11)
(C++11)
(C++11)
Flutuando funções de manipulação de pontos
Original:
Floating point manipulation functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
ldexp
scalbn
scalbln
(C++11)
(C++11)
ilogb(C++11)
logb(C++11)
frexp
modf
nextafter
nexttoward
(C++11)
(C++11)
copysign(C++11)
Classificação / Comparação
Original:
Classification/Comparison
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
fpclassify(C++11)
isfinite(C++11)
isinf(C++11)
isnan(C++11)
isnormal(C++11)
signbit(C++11)
isgreater(C++11)
isgreaterequal(C++11)
isless(C++11)
islessequal(C++11)
islessgreater(C++11)
isunordered(C++11)
Constantes de macros
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.
FP_NORMAL
FP_SUBNORMAL
FP_ZERO
FP_INFINITE
FP_NAN
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
 
Defined in header <cmath>
int         ilogb( float arg );
(a partir do C++ 11)
int         ilogb( double arg );
(a partir do C++ 11)
int         ilogb( long double arg );
(a partir do C++ 11)
double      ilogb( Integral arg );
(a partir do C++ 11)
#define FP_ILOGB0 /*implementation-defined*/
(a partir do C++ 11)
#define FP_ILOGBNAN /*implementation-defined*/
(a partir do C++ 11)

Extracts the value of the exponent from the floating-point argument arg, and returns it as a signed integer value. Formally, the result is the integral part of log
r
|arg|
as a signed integral value, for non-zero arg, where r is std::numeric_limits<T>::radix and T is the floating-point type of arg.

Índice

[editar] Parâmetros

arg -
flutuando valor de ponto
Original:
floating point value
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[editar] Valor de retorno

The floating-point exponent, cast to integer, as if by static_cast<int>(std::logb(arg)).

Erro domínio ou intervalo pode ocorrer se arg é zero, FP_ILOGB0 é retornado, nesse caso,.
Original:
Domain or range error may occur if arg is zero, FP_ILOGB0 is returned in that case.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Erro de domínio ou intervalo pode ocorrer se arg é infinito, MAX_INT é devolvido em caso.
Original:
Domain or range error may occur if arg is infinite, MAX_INT is returned in that case.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Erro de domínio ou intervalo pode ocorrer se arg é NaN, FP_ILOGBNAN é devolvido em caso.
Original:
Domain or range error may occur if arg is NaN, FP_ILOGBNAN is returned in that case.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
Se o resultado não pode ser representado como int, o resultado é indefinido.
Original:
If the result cannot be represented as int, the result is undefined.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[editar] Notas

O valor do expoente retornado por std::ilogb é sempre 1 a menos do que o expoente retuned std::frexp por causa das exigências de normalização diferentes: para o expoente e retornado por std::ilogb, |arg*r-e
|
está entre 1 e r (tipicamente entre 1 e 2), mas para o expoente e retornado por std::frexp, |arg*2-e
|
é entre 0.5 e 1.
Original:
The value of the exponent returned by std::ilogb is always 1 less than the exponent retuned by std::frexp because of the different normalization requirements: for the exponent e returned by std::ilogb, |arg*r-e
|
is between 1 and r (typically between 1 and 2), but for the exponent e returned by std::frexp, |arg*2-e
|
is between 0.5 and 1.
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

[editar] Exemplo

Compara diferentes funções de ponto flutuante de decomposição
Original:
Compares different floating-point decomposition functions
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

#include <iostream>
#include <cmath>
#include <limits>
int main()
{
    double f = 123.45;
    std::cout << "Given the number " << f << " or " << std::hexfloat
              << f << std::defaultfloat << " in hex,\n";
 
    double f3;
    double f2 = std::modf(f, &f3);
    std::cout << "modf() makes " << f3 << " + " << f2 << '\n';
 
    int i;
    f2 = std::frexp(f, &i);
    std::cout << "frexp() makes " << f2 << " * 2^" << i << '\n';
 
    i = std::ilogb(f);
    std::cout << "logb()/ilogb() make " << f/std::scalbn(1.0, i) << " * "
              << std::numeric_limits<double>::radix
              << "^" << std::ilogb(f) << '\n';
}

Output:

Given the number 123.45 or 0x1.edccccccccccdp+6 in hex,
modf() makes 123 + 0.45
frexp() makes 0.964453 * 2^7
logb()/ilogb() make 1.92891 * 2^6

[editar] Veja também

decompõe um número em significand e um poder de 2
Original:
decomposes a number into significand and a power of 2
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(função) [edit]
(C++11)
extrai expoente do número
Original:
extracts exponent of the number
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(função) [edit]
(C++11)
(C++11)
multiplica um número por FLT_RADIX elevado a uma potência
Original:
multiplies a number by FLT_RADIX raised to a power
The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.

(função) [edit]