log10(3) [plan9 man page]
LOG10(3) Linux Programmer's Manual LOG10(3) NAME
log10, log10f, log10l - base-10 logarithmic function SYNOPSIS
#include <math.h> double log10(double x); float log10f(float x); long double log10l(long double x); Link with -lm. Feature Test Macro Requirements for glibc (see feature_test_macros(7)): log10f(), log10l(): _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE DESCRIPTION
These functions return the base 10 logarithm of x. RETURN VALUE
On success, these functions return the base 10 logarithm of x. For special cases, including where x is 0, 1, negative, infinity, or NaN, see log(3). ERRORS
See math_error(7) for information on how to determine whether an error has occurred when calling these functions. For a discussion of the errors that can occur for these functions, see log(3). ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7). +-----------------------------+---------------+---------+ |Interface | Attribute | Value | +-----------------------------+---------------+---------+ |log10(), log10f(), log10l() | Thread safety | MT-Safe | +-----------------------------+---------------+---------+ CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008. The variant returning double also conforms to SVr4, 4.3BSD, C89. SEE ALSO
cbrt(3), clog10(3), exp10(3), log(3), log2(3), sqrt(3) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. 2017-09-15 LOG10(3)
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log10(3M) Mathematical Library Functions log10(3M) NAME
log10, log10f, log10l - base 10 logarithm function SYNOPSIS
c99 [ flag... ] file... -lm [ library... ] #include <math.h> double log10(double x); float log10f(float x); long double log10l(long double x); DESCRIPTION
These functions compute the base 10 logarithm of x, log(10)(x). RETURN VALUES
Upon successful completion, log10() returns the base 10 logarithm of x. If x is +-0, a pole error occurs and log10(), log10f(), and log10l() return -HUGE_VAL, -HUGE_VALF, and -HUGE_VALL, respectively. For finite values of x that are less than 0, or if x is -Inf, a domain error occurs and a NaN is returned. If x is NaN, a NaN is returned. If x is 1, +0 is returned. If x is +Inf, x is returned. For exceptional cases, matherr(3M) tabulates the values to be returned by log10() as specified by SVID3 and XPG3. ERRORS
These functions will fail if: Domain Error The finite value of x is negative, or x is -Inf. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the invalid floating-point exception is raised. The log10() function sets errno to EDOM if the value of x is negative. Pole Error The value of x is 0. If the integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero, the divide-by-zero floating-point exception is raised. USAGE
An application wanting to check for exceptions should call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an exception has been raised. An application should either examine the return value or check the floating point exception flags to detect exceptions. An application can also set errno to 0 before calling log10(). On return, if errno is non-zero, an error has occurred. The log10f() and log10l() functions do not set errno. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
feclearexcept(3M), fetestexcept(3M), isnan(3M), log(3M), math.h(3HEAD), matherr(3M), pow(3M), attributes(5), standards(5) SunOS 5.11 12 Jul 2006 log10(3M)