| Common mathematical functions | |||||||||||||||||||||||||||||||
| Mathematical special functions(C++17) | |||||||||||||||||||||||||||||||
| Mathematical constants(C++20) | |||||||||||||||||||||||||||||||
| Basic linear algebra algorithms(C++26) | |||||||||||||||||||||||||||||||
| Data-parallel types (SIMD)(C++26) | |||||||||||||||||||||||||||||||
| Floating-point environment(C++11) | |||||||||||||||||||||||||||||||
| Complex numbers | |||||||||||||||||||||||||||||||
Numeric array (valarray) | |||||||||||||||||||||||||||||||
| Pseudo-random number generation | |||||||||||||||||||||||||||||||
| Bit manipulation(C++20) | |||||||||||||||||||||||||||||||
| Saturation arithmetic(C++26) | |||||||||||||||||||||||||||||||
| Factor operations | |||||||||||||||||||||||||||||||
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| Interpolations | |||||||||||||||||||||||||||||||
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| Generic numeric operations | |||||||||||||||||||||||||||||||
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| C-style checked integer arithmetic | |||||||||||||||||||||||||||||||
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| Nearest integer floating point operations | |||||||||||||||||||||||||||||||||||||||||
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| Floating point manipulation functions | |||||||||||||||||||||||||||||||||||||||||
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| Classification and comparison | |||||||||||||||||||||||||||||||||||||||||
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| Types | |||||||||||||||||||||||||||||||||||||||||
| Macro constants | |||||||||||||||||||||||||||||||||||||||||
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Defined in header <cmath> | ||
| (1) | ||
float exp2(float num); double exp2(double num); | (until C++23) | |
/*floating-point-type*/ exp2(/*floating-point-type*/ num); | (since C++23) (constexpr since C++26) | |
float exp2f(float num); | (2) | (since C++11) (constexpr since C++26) |
longdouble exp2l(longdouble num); | (3) | (since C++11) (constexpr since C++26) |
SIMD overload(since C++26) | ||
Defined in header <simd> | ||
template</*math-floating-point*/ V> constexpr/*deduced-simd-t*/<V> | (S) | (since C++26) |
Additional overloads(since C++11) | ||
Defined in header <cmath> | ||
template<class Integer> double exp2( Integer num); | (A) | (constexpr since C++26) |
std::exp2 for all cv-unqualified floating-point types as the type of the parameter.(since C++23)S) The SIMD overload performs an element-wise std::exp2 onv_num.
| (since C++26) |
A) Additional overloads are provided for all integer types, which are treated asdouble. | (since C++11) |
Contents |
| num | - | floating-point or integer value |
If no errors occur, the base-2 exponential ofnum (2num
) is returned.
If a range error due to overflow occurs,+HUGE_VAL,+HUGE_VALF, or+HUGE_VALL is returned.
If a range error occurs due to underflow, the correct result (after rounding) is returned.
Errors are reported as specified inmath_errhandling.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
The additional overloads are not required to be provided exactly as(A). They only need to be sufficient to ensure that for their argumentnum of integer type,std::exp2(num) has the same effect asstd::exp2(static_cast<double>(num)).
For integral exponents, it may be preferable to usestd::ldexp.
#include <cerrno>#include <cfenv>#include <cmath>#include <cstring>#include <iostream> // #pragma STDC FENV_ACCESS ON int main(){std::cout<<"exp2(4) = "<< std::exp2(4)<<'\n'<<"exp2(0.5) = "<< std::exp2(0.5)<<'\n'<<"exp2(-4) = "<< std::exp2(-4)<<'\n'; // special valuesstd::cout<<"exp2(-0) = "<< std::exp2(-0.0)<<'\n'<<"exp2(-Inf) = "<< std::exp2(-INFINITY)<<'\n'; // error handlingerrno=0;std::feclearexcept(FE_ALL_EXCEPT);constdouble inf= std::exp2(1024);constbool is_range_error=errno==ERANGE; std::cout<<"exp2(1024) = "<< inf<<'\n';if(is_range_error)std::cout<<" errno == ERANGE: "<<std::strerror(ERANGE)<<'\n';if(std::fetestexcept(FE_OVERFLOW))std::cout<<" FE_OVERFLOW raised\n";}
Possible output:
exp2(4) = 16exp2(0.5) = 1.41421exp2(-4) = 0.0625exp2(-0) = 1exp2(-Inf) = 0exp2(1024) = inf errno == ERANGE: Numerical result out of range FE_OVERFLOW raised
(C++11)(C++11) | returnse raised to the given power (\({\small e^x}\)ex) (function)[edit] |
(C++11)(C++11)(C++11) | returnse raised to the given power, minus1 (\({\small e^x-1}\)ex-1) (function)[edit] |
(C++11)(C++11) | multiplies a number by2 raised to an integral power (function)[edit] |
(C++11)(C++11)(C++11) | base2 logarithm of the given number (\({\small\log_{2}{x}}\)log2(x)) (function)[edit] |
C documentation forexp2 | |
