float log10f( float arg );
(1) (since C99)double log10( double arg );
(2)long double log10l( long double arg );
(3) (since C99)#define log10( arg )
(4) (since C99)1-3) Computes the common (base-10) logarithm of arg.
4) Type-generic macro: If arg has type long double, log10l is called. Otherwise, if arg has integer type or the type double, log10 is called. Otherwise, log10f is called.
If no errors occur, the common (base-10) logarithm of arg (log10(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.
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),
#include <errno.h>
#include <fenv.h>
#include <float.h>
#include <math.h>
#include <stdio.h>
// #pragma STDC FENV_ACCESS ON
int main(void)
{
printf("log10(1000) = %f\n", log10(1000));
printf("log10(0.001) = %f\n", log10(0.001));
printf("base-5 logarithm of 125 = %f\n", log10(125) / log10(5));
// special values
printf("log10(1) = %f\n", log10(1));
printf("log10(+Inf) = %f\n", log10(INFINITY));
// error handling
errno = 0; feclearexcept(FE_ALL_EXCEPT);
printf("log10(0) = %f\n", log10(0));
if (errno == ERANGE)
perror(" errno == ERANGE");
if (fetestexcept(FE_DIVBYZERO))
puts(" FE_DIVBYZERO raised");
}
Possible output:
log10(1000) = 3.000000
log10(0.001) = -3.000000
base-5 logarithm of 125 = 3.000000
log10(1) = 0.000000
log10(+Inf) = inf
log10(0) = -inf
errno == ERANGE: Numerical result out of range
FE_DIVBYZERO raised[edit] References
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