| Defined in header <cmath> | ||
|---|---|---|
float log10( float arg ); | (1) | |
double log10( double arg ); | (2) | |
long double log10( long double arg ); | (3) | |
double log10( Integral 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_DIVBYZEROis raised. - If the argument is 1, +0 is returned
- If the argument is negative, NaN is returned and
FE_INVALIDis raised. - If the argument is +∞, +∞ is returned
- If the argument is NaN, NaN is returned
Example
#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 raisedSee also
| computes natural (base e) logarithm (to base e) (ln(x)) (function) | |
| (C++11) | base 2 logarithm of the given number (log2(x)) (function) |
| (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) | |
C documentation for log10 | |
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