std::acosh,...std::acoshl(3)

💖 std::acosh, std::acoshf, std::acoshl — C++ Standard Library 💖

okay bestie, this is the page for std::acosh, std::acoshf, and std::acoshl — the inverse hyperbolic cosine girlies of the C++ Standard Library. They live in <cmath>, and they’re here to do math with main character energy. ✨

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🌸 NAME 🌸

std::acosh, std::acoshf, std::acoshl

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✨ Synopsis ✨

First things first, bestie: this whole family is defined in header <cmath>. Here’s the full lineup, exactly as it appears — no cap, every overload is invited to the party:

Defined in header <cmath>
float       acosh ( float num );

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

long double acosh ( long double num );
/* floating-point-type */                                    (since C++23)
            acosh ( /* floating-point-type */ num );
(constexpr since C++26)
float       acoshf( float num );                     (1) (2) (since C++11)
                                                                 (constexpr since C++26)
long double acoshl( 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      acosh ( Integer num );

So like, 1-3) computes the inverse hyperbolic cosine of num. Slay.

The library provides overloads of std::acosh 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.

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🎀 Parameters 🎀

• num — floating-point or integer value

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🦋 Return value 🦋

If no errors occur, the inverse hyperbolic cosine of num (cosh-1 (num), or arcosh(num)) on the interval [0, +∞], is returned. Literally giving math.

If a domain error occurs, an implementation-defined value is returned (NaN where supported). So if things go weird, that’s the vibe the implementation picked. 😭

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💅 Error handling 💅

Errors are reported as specified in math_errhandling.

If the argument is less than 1, a domain error occurs.

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

• if the argument is less than 1, FE_INVALID is raised an NaN is returned.
• if the argument is 1, +0 is returned.
• if the argument is +∞, +∞ is returned.
• if the argument is NaN, NaN is returned.

bestie, the “less than 1” thing is the domain-error zone. Treat it with respect. 🫶

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🌈 Notes 🌈

Although the C standard (to which C++ refers for this function) names this function “arc hyperbolic cosine”, the inverse functions of the hyperbolic functions are the area functions. Their argument is the area of a hyperbolic sector, not an arc. The correct name is “inverse hyperbolic cosine” (used by POSIX) or “area hyperbolic cosine”. ikyk. 💜

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::acosh(num) has the same effect as std::acosh(static_cast<double>(num)). periodt. ✨

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💻 Examples 💻

// Run this code

#include <cerrno>
#include <cfenv>
#include <cfloat>
#include <cmath>
#include <cstring>
#include <iostream>

// #pragma STDC FENV_ACCESS ON

int main()
{
    std::cout << "acosh(1) = " << std::acosh(1) << '\n'
              << "acosh(10) = " << std::acosh(10) << '\n'
              << "acosh(DBL_MAX) = " << std::acosh(DBL_MAX) << '\n'
              << "acosh(Inf) = " << std::acosh(INFINITY) << '\n';

    // error handling
    errno = 0;
    std::feclearexcept(FE_ALL_EXCEPT);

    std::cout << "acosh(0.5) = " << std::acosh(0.5) << '\n';

    if (errno == EDOM)
        std::cout << "    errno == EDOM: " << std::strerror(errno) << '\n';
    if (std::fetestexcept(FE_INVALID))
        std::cout << "    FE_INVALID raised\n";
}

🌟 Possible output 🌟

acosh(1) = 0
acosh(10) = 2.99322
acosh(DBL_MAX) = 710.476
acosh(Inf) = inf
acosh(0.5) = -nan
    errno == EDOM: Numerical argument out of domain
    FE_INVALID raised

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👀 See also 👀

• asinh, asinhf, asinhl — computes the inverse hyperbolic sine (arsinh(x)) (C++11) (function)
• atanh, atanhf, atanhl — computes the inverse hyperbolic tangent (artanh(x)) (C++11) (function)
• cosh, coshf, coshl — computes hyperbolic cosine (cosh(x)) (C++11) (function)
• acosh(std::complex) — computes area hyperbolic cosine of a complex number (arcosh(z)) (C++11) (function template)
• C documentation for acosh

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🔥 External links 🔥

• Weisstein, Eric W. “Inverse Hyperbolic Cosine.” From MathWorld — A Wolfram Web Resource.

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source: cppreference.com · date/version: 2024.06.10 · page: std::acosh,...std::acoshl(3) 🌸