std::log10,...std::log10l(3)

🎀 NAME 🎀

okay so bestie, this is the std::log10, std::log10f, and std::log10l page from the C++ Standard Library, section 3 — and yes, the name line is literally:

std::log10,std::log10f,std::log10l - std::log10,std::log10f,std::log10l

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🌸 Synopsis 🌸

Defined in header <cmath>
float       log10 ( float num );

double      log10 ( double num );                            (until C++23)

long double log10 ( long double num );
/* floating-point-type */                                    (since C++23)
                log10 ( /* floating-point-type */ num );
(constexpr since C++26)
float       log10f( float num );                     (1) (2) (since C++11)
                                                     (constexpr since C++26)
long double log10l( 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      log10 ( Integer num );

• 1-3) Computes the common (base-10) logarithm of num.
• The library provides overloads of std::log10 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 treated as double. (since C++11)

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💖 Parameters 💖

• num — floating-point or integer value.

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✨ Return value ✨

If no errors occur, the common (base-10) logarithm of num (log10(num) or lg(num)) is returned.

If a domain error occurs, an implementation-defined value is returned (NaN where supported).

If a pole error occurs, -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL is returned.

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🚨 Error handling 🚨

Errors are reported as specified in math_errhandling.

Domain error occurs if num is less than zero.

Pole error may occur if num is zero.

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

• If the argument is ±0, -∞ is returned and FE_DIVBYZERO is raised.
• If the argument is 1, +0 is returned.
• If the argument is negative, NaN is returned and FE_INVALID is raised.
• If the argument is +∞, +∞ is returned.
• If the argument is NaN, NaN is returned.

bestie heads up: negative num is a domain-error situation, and zero may give you a pole error. math is dramatic like that sometimes 💀

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📝 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::log10(num) has the same effect as std::log10(static_cast<double>(num)).

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🧪 Example 🧪

// Run this code

#include <cerrno>
#include <cfenv>
#include <cmath>
#include <cstring>
#include <iostream>
// #pragma STDC FENV_ACCESS ON

int main()
{
    std::cout << "log10(1000) = " << std::log10(1000) << '\n'
              << "log10(0.001) = " << std::log10(0.001) << '\n'
              << "base-5 logarithm of 125 = "
              << std::log10(125) / std::log10(5) << '\n';

    // special values
    std::cout << "log10(1) = " << std::log10(1) << '\n'
              << "log10(+Inf) = " << std::log10(INFINITY) << '\n';

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

    std::cout << "log10(0) = " << std::log10(0) << '\n';

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

Possible output:

log10(1000) = 3
log10(0.001) = -3
base-5 logarithm of 125 = 3
log10(1) = 0
log10(+Inf) = inf
log10(0) = -inf
    errno == ERANGE: Numerical result out of range
    FE_DIVBYZERO raised

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👀 See also 👀

• log, logf, logl — computes natural (base e) logarithm \({\small\ln{x}}\)ln(x) (function) (C++11) (C++11)
• log2, log2f, log2l — base 2 logarithm of the given number \({\small\log_{2}{x}}\)log[2](x) (function) (C++11) (C++11)
• log1p, log1pf, log1pl — natural logarithm (to base e) of 1 plus the given number \({\small\ln{(1+x)}}\)ln(1+x) (function) (C++11) (C++11)
• log10(std::complex) — complex common logarithm with the branch cuts along the negative real axis (function template)
• log10(std::valarray) — applies the function std::log10 to each element of valarray (function template)
• C documentation for log10

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okay that’s the whole base-10 vibe — source http://cppreference.com, version/date 2024.06.10, page std::log10,...std::log10l(3); go log some slay 💅✨