std::log10, std::log10f, std::log10l
From cppreference.com
Defined in header <cmath>
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(1) | ||
float log10 ( float arg ); |
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float log10f( float arg ); |
(since C++11) | |
double log10 ( double arg ); |
(2) | |
(3) | ||
long double log10 ( long double arg ); |
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long double log10l( long double arg ); |
(since C++11) | |
double log10 ( IntegralType arg ); |
(4) | (since C++11) |
1-3) Computes the common (base-10) logarithm of
arg
.4) A set of overloads or a function template accepting an argument of any integral type. Equivalent to 2) (the argument is cast to double).
Parameters
arg | - | value of floating-point or Integral type |
Return value
If no errors occur, the common (base-10) logarithm of arg
(log
10(arg) or lg(arg)) 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.
Error handling
Errors are reported as specified in math_errhandling.
Domain error occurs if arg
is less than zero.
Pole error may occur if arg
is zero.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
- 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
Example
Run this code
#include <iostream> #include <cmath> #include <cerrno> #include <cstring> #include <cfenv> // #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
See also
(C++11)(C++11) |
computes natural (base e) logarithm (ln(x)) (function) |
(C++11)(C++11)(C++11) |
base 2 logarithm of the given number (log2(x)) (function) |
(C++11)(C++11)(C++11) |
natural logarithm (to base e) of 1 plus the given number (ln(1+x)) (function) |
complex common logarithm with the branch cuts along the negative real axis (function template) | |
applies the function std::log10 to each element of valarray (function template) |