Man page or keyword search:   man All Sections 1 - General Commands 2 - System Calls 3 - Subroutines, Functions 4 - Special Files 5 - File Formats 6 - Games and Screensavers 7 - Macros and Conventions 8 - Maintenence Commands 9 - Kernel Interface New Commands Server 4.4BSD AIX Alpinelinux Archlinux Aros BSDOS BSDi Bifrost CentOS Cygwin Darwin Debian DigitalUNIX DragonFly ElementaryOS Fedora FreeBSD Gentoo GhostBSD HP-UX Haiku Hurd IRIX Inferno JazzOS Kali Knoppix LinuxMint MacOSX Mageia Mandriva Manjaro Minix MirBSD NeXTSTEP NetBSD OPENSTEP OSF1 OpenBSD OpenDarwin OpenIndiana OpenMandriva OpenServer OpenSuSE OpenVMS Oracle PC-BSD Peanut Pidora Plan9 QNX Raspbian RedHat Scientific Slackware SmartOS Solaris SuSE SunOS Syllable Tru64 UNIXv7 Ubuntu Ultrix UnixWare Xenix YellowDog aLinux   9087 pages apropos Keyword Search (all sections) Output format html ascii pdf view pdf save postscript

LOG(3)			 BSD Library Functions Manual			LOG(3)

NAME
     log, logf, log10, log10f, log1p, log1pf log2, log2f, — logarithm func‐
     tions

LIBRARY
     Math Library (libm, -lm)

SYNOPSIS
     #include <math.h>

     double
     log(double x);

     float
     logf(float x);

     double
     log10(double x);

     float
     log10f(float x);

     double
     log1p(double x);

     float
     log1pf(float x);

     double
     log2(double x);

     float
     log2f(float x);

DESCRIPTION
     The following functions compute logarithms:

       ·   The log() and logf() functions return the natural logarithm.

       ·   The log10() and log10f() functions return the base 10 logarithm.

       ·   The log1p() and log1pf() functions return the natural logarithm of
	   (1.0 + x) accurately even for very small values of x.

       ·   The log2() and log2f() functions return the base 2 logarithm.

RETURN VALUES
     Upon successful completion, the functions return the logarithm of x as
     descibed above.  Otherwise the following may occur:

	   1.	If x is NaN, all functions return NaN.

	   2.	If x is positive infinity, all functions return x.  If x is
		negative infinity, all functions return NaN.

	   3.	If x is +0.0 or -0.0, the log(), log10(), and log2() families
		return either -HUGE_VAL, -HUGE_VALF, or -HUGE_VALL, whereas
		the log1p() family returns x.

	   4.	If x is +1.0, the log(), log10(), and log2() families return
		+0.0.  If x is -1.0, the log1p() family returns -HUGE_VAL,
		-HUGE_VALF, or -HUGE_VALL.

     In addition, on a VAX, errno is set to EDOM and the reserved operand is
     returned by log() unless x > 0, by log1p() unless x > -1.

SEE ALSO
     exp(3), ilogb(3), math(3)

STANDARDS
     The described functions conform to ISO/IEC 9899:1999 (“ISO C99”).

HISTORY
     The history of the logarithm functions dates back to Version 6 AT&T UNIX.

BSD			      September 13, 2011			   BSD

                             _         _         _ 
                            | |       | |       | |     
                            | |       | |       | |     
                         __ | | __ __ | | __ __ | | __  
                         \ \| |/ / \ \| |/ / \ \| |/ /  
                          \ \ / /   \ \ / /   \ \ / /   
                           \   /     \   /     \   /    
                            \_/       \_/       \_/ 

Vote for polarhome