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diff --git a/man/man3/log1p.3 b/man/man3/log1p.3 new file mode 100644 index 000000000..7855e6772 --- /dev/null +++ b/man/man3/log1p.3 @@ -0,0 +1,150 @@ +'\" t +.\" Copyright 1995 Jim Van Zandt <jrv@vanzandt.mv.com> +.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" Modified 2002-07-27 by Walter Harms +.\" (walter.harms@informatik.uni-oldenburg.de) +.TH log1p 3 (date) "Linux man-pages (unreleased)" +.SH NAME +log1p, log1pf, log1pl \- logarithm of 1 plus argument +.SH LIBRARY +Math library +.RI ( libm ", " \-lm ) +.SH SYNOPSIS +.nf +.B #include <math.h> +.P +.BI "double log1p(double " x ); +.BI "float log1pf(float " x ); +.BI "long double log1pl(long double " x ); +.P +.fi +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.P +.nf +.BR log1p (): + _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L + || _XOPEN_SOURCE >= 500 +.\" || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED + || /* Since glibc 2.19: */ _DEFAULT_SOURCE + || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE +.fi +.P +.BR log1pf (), +.BR log1pl (): +.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 a value equivalent to +.P +.nf + log (1 + \fIx\fP) +.fi +.P +The result is computed in a way +that is accurate even if the value of +.I x +is near zero. +.SH RETURN VALUE +On success, these functions return the natural logarithm of +.IR "(1\ +\ x)" . +.P +If +.I x +is a NaN, +a NaN is returned. +.P +If +.I x +is positive infinity, positive infinity is returned. +.P +If +.I x +is \-1, a pole error occurs, +and the functions return +.RB \- HUGE_VAL , +.RB \- HUGE_VALF , +or +.RB \- HUGE_VALL , +respectively. +.P +If +.I x +is less than \-1 (including negative infinity), +a domain error occurs, +and a NaN (not a number) is returned. +.\" POSIX.1 specifies a possible range error if x is subnormal +.\" glibc 2.8 doesn't do this +.SH ERRORS +See +.BR math_error (7) +for information on how to determine whether an error has occurred +when calling these functions. +.P +The following errors can occur: +.TP +Domain error: \fIx\fP is less than \-1 +.I errno +is set to +.B EDOM +(but see BUGS). +An invalid floating-point exception +.RB ( FE_INVALID ) +is raised. +.TP +Pole error: \fIx\fP is \-1 +.I errno +is set to +.B ERANGE +(but see BUGS). +A divide-by-zero floating-point exception +.RB ( FE_DIVBYZERO ) +is raised. +.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 log1p (), +.BR log1pf (), +.BR log1pl () +T} Thread safety MT-Safe +.TE +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +C99, POSIX.1-2001. +.\" BSD +.SH BUGS +Before glibc 2.22, the glibc implementation did not set +.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6792 +.I errno +to +.B EDOM +when a domain error occurred. +.P +Before glibc 2.22, the glibc implementation did not set +.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6792 +.I errno +to +.B ERANGE +when a range error occurred. +.SH SEE ALSO +.BR exp (3), +.BR expm1 (3), +.BR log (3) |