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Compute the logarithm (base 10) of a number
#include <math.h>
double log10( double x );
float log10f( float x );
- x
- The number that you want to compute the log of.
libm
Use the -l m option to
qcc
to link against this library.
The log10() and log10f() functions compute the base 10 logarithm of x:
log10 x
A domain error occurs if x is negative.
A range error occurs if x is zero.
The base 10 logarithm of x.
|
If an error occurs, these functions return 0, but this is also a valid
mathematical result.
If you want to check for errors, set
errno
to 0, call the function, and then check errno again.
These functions don't change errno if no errors occurred. |
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main( void )
{
printf( "%f\n", log10(.5) );
return EXIT_SUCCESS;
}
produces the output:
-0.301030
ANSI,
POSIX 1003.1
Safety: | |
Cancellation point |
No |
Interrupt handler |
No |
Signal handler |
No |
Thread |
Yes |
errno,
exp(),
log(),
pow()
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