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log10 |
Portability: | ISO/ANSI C conforming, UNIX compatible |
SYNOPSIS | |
DESCRIPTION | |
RETURN VALUE | |
DIAGNOSTICS | |
EXAMPLE | |
RELATED FUNCTIONS | |
SEE ALSO |
SYNOPSIS |
#include <math.h> double log10(double x);
DESCRIPTION |
log10
computes the common (base 10) log of its argument
x
. The
x
argument must be a positive
double-precision, floating-point number.
RETURN VALUE |
log10
returns the common log of its argument, expressed as a double-precision, floating-point
number.
DIAGNOSTICS |
If
x
is negative or 0,
log10
returns
-HUGE_VAL
. In this case, the run-time library also writes an error
message to the standard error file (
stderr
).
If an error occurs in
log10
, the
_matherr
routine is called.
You supply your own version of
_matherr
to suppress the diagnostic message or modify the value returned.
EXAMPLE |
This example calculates the common log
of RATE, and rounds up using
log10
:
#include <math.h> #include <stdio.h> #define RATE .017 main() { double y; y = ceil(log10(RATE)); /* Print the "order of magnitude" of RATE. */ printf("ceil(log10(%f)) = %f\n", RATE, y); }
RELATED FUNCTIONS |
SEE ALSO |
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