std::exp2,s...f,std::exp2l(3)

okay bestie, welcome to the std::exp2,s...f,std::exp2l(3) page from the C++ Standard Libary manual 💅 (yes, the header literally has that s...f moment, and we are keeping it).

🌸 NAME 🌸

std::exp2, std::exp2f, std::exp2l — the official NAME line is exactly std::exp2,std::exp2f,std::exp2l - std::exp2,std::exp2f,std::exp2l. Iconic. No notes.

✨ Synopsis ✨

Here's the full overload roster, bestie — version tags, labels, all of it, do not lose a crumb:

Defined in header <cmath>

float       exp2 ( float num );

double      exp2 ( double num );                            (until C++23)

long double exp2 ( long double num );
/* floating-point-type */                                   (since C++23)
            exp2 ( /* floating-point-type */ num );
(constexpr since C++26)

float       exp2f( float num );                     (1) (2) (since C++11)
                                                         (constexpr since C++26)

long double exp2l( long double num );                   (3) (since C++11)
                                                         (constexpr since C++26)

Additional overloads (since C++11)
Defined in header <cmath>

template< class Integer >                               (A)
(constexpr since C++26)
double      exp2 ( Integer num );

1-3) Computes 2 raised to the given power num.

The library provides overloads of std::exp2 for all cv-unqualified floating-point types as the type of the parameter. (since C++23)

A) Additional overloads are provided for all integer types, which are (since C++11) treated as double.

🫶 Parameters 🫶

• num — floating-point or integer value. That's the whole parameter list, bestie. 💖

🎀 Return value 🎀

If no errors occur, the base-2 exponential of num (2num in the page's own notation) 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.

💀 Error handling 💀

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559), then:

• If the argument is ±0, 1 is returned.
• If the argument is -∞, +0 is returned.
• If the argument is +∞, +∞ is returned.
• If the argument is NaN, NaN is returned.

🧠 Notes 🧠

The additional overloads are not required to be provided exactly as (A). They only need to be sufficient to ensure that for their argument num of integer type, std::exp2(num) has the same effect as std::exp2(static_cast<double>(num)).

For integral exponents, it may be preferable to use std::ldexp.

🍓 Example 🍓

The example says // Run this code, so:

#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 values
    std::cout << "exp2(-0) = " << std::exp2(-0.0) << '\n'
              << "exp2(-Inf) = " << std::exp2(-INFINITY) << '\n';

    // error handling
    errno = 0;
    std::feclearexcept(FE_ALL_EXCEPT);
    const double inf = std::exp2(1024);
    const bool 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) = 16
exp2(0.5) = 1.41421
exp2(-4) = 0.0625
exp2(-0) = 1
exp2(-Inf) = 0
exp2(1024) = inf
    errno == ERANGE: Numerical result out of range
    FE_OVERFLOW raised

🌈 See also 🌈

• exp, expf, expl — returns e raised to the given power (\({\small e^x}\)e^x) (function) (C++11) (C++11).
• expm1, expm1f, expm1l — returns e raised to the given power, minus one (\({\small e^x-1}\)e^x-1) (C++11) (function) (C++11) (C++11).
• ldexp, ldexpf, ldexpl — multiplies a number by 2 raised to an integral power (function) (C++11) (C++11).
• log2, log2f, log2l — base 2 logarithm of the given number (\({\small\log_{2}{x}}\)log[2](x)) (C++11) (function) (C++11) (C++11).
• C documentation for exp2

kisses and sparkles 💖 — this page came from http://cppreference.com, dated 2024.06.10, and its page tag is std::exp2,s...f,std::exp2l(3). Byeee 🎀