'\" t .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk .\" .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .\" References consulted: .\" Linux libc source code .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) .\" 386BSD man pages .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) .\" Modified 1995-08-14 by Arnt Gulbrandsen .\" Modified 2002-07-27 by Walter Harms .\" (walter.harms@informatik.uni-oldenburg.de) .\" .TH log10 3 2023-07-20 "Linux man-pages 6.05.01" .SH NAME log10, log10f, log10l \- base-10 logarithmic function .SH LIBRARY Math library .RI ( libm ", " \-lm ) .SH SYNOPSIS .nf .B #include .PP .BI "double log10(double " x ); .BI "float log10f(float " x ); .BI "long double log10l(long double " x ); .fi .PP .RS -4 Feature Test Macro Requirements for glibc (see .BR feature_test_macros (7)): .RE .PP .BR log10f (), .BR log10l (): .nf _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE .fi .SH DESCRIPTION These functions return the base 10 logarithm of .IR x . .SH RETURN VALUE On success, these functions return the base 10 logarithm of .IR x . .PP For special cases, including where .I x is 0, 1, negative, infinity, or NaN, see .BR log (3). .SH ERRORS See .BR math_error (7) for information on how to determine whether an error has occurred when calling these functions. .PP For a discussion of the errors that can occur for these functions, see .BR log (3). .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7). .TS allbox; lbx lb lb l l l. Interface Attribute Value T{ .na .nh .BR log10 (), .BR log10f (), .BR log10l () T} Thread safety MT-Safe .TE .sp 1 .SH STANDARDS C11, POSIX.1-2008. .SH HISTORY C99, POSIX.1-2001. .PP The variant returning .I double also conforms to SVr4, 4.3BSD, C89. .SH SEE ALSO .BR cbrt (3), .BR clog10 (3), .BR exp10 (3), .BR log (3), .BR log2 (3), .BR sqrt (3)