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Diffstat (limited to 'man/man3/expm1.3')
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diff --git a/man/man3/expm1.3 b/man/man3/expm1.3 new file mode 100644 index 000000000..0e093a617 --- /dev/null +++ b/man/man3/expm1.3 @@ -0,0 +1,165 @@ +'\" 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 Walter Harms +.\" (walter.harms@informatik.uni-oldenburg.de) +.\" +.TH expm1 3 (date) "Linux man-pages (unreleased)" +.SH NAME +expm1, expm1f, expm1l \- exponential minus 1 +.SH LIBRARY +Math library +.RI ( libm ", " \-lm ) +.SH SYNOPSIS +.nf +.B #include <math.h> +.P +.BI "double expm1(double " x ); +.BI "float expm1f(float " x ); +.BI "long double expm1l(long double " x ); +.P +.fi +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.P +.BR expm1 (): +.nf + _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 expm1f (), +.BR expm1l (): +.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 + exp(x) \- 1 +.fi +.P +The result is computed in a way that is accurate even if the value of +.I x +is near +zero\[em]a case where +.I "exp(x) \- 1" +would be inaccurate due to +subtraction of two numbers that are nearly equal. +.SH RETURN VALUE +On success, these functions return +.IR "exp(x)\ \-\ 1" . +.P +If +.I x +is a NaN, +a NaN is returned. +.P +If +.I x +is +0 (\-0), ++0 (\-0) is returned. +.P +If +.I x +is positive infinity, positive infinity is returned. +.P +If +.I x +is negative infinity, \-1 is returned. +.P +If the result overflows, a range error occurs, +and the functions return +.RB \- HUGE_VAL , +.RB \- HUGE_VALF , +or +.RB \- HUGE_VALL , +respectively. +.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 +Range error, overflow +.I errno +is set to +.B ERANGE +(but see BUGS). +An overflow floating-point exception +.RB ( FE_OVERFLOW ) +is raised. +.\" +.\" POSIX.1 specifies an optional range error (underflow) if +.\" x is subnormal. glibc does not implement this. +.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 expm1 (), +.BR expm1f (), +.BR expm1l () +T} Thread safety MT-Safe +.TE +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +C99, POSIX.1-2001. +BSD. +.SH BUGS +Before glibc 2.17, +.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6778 +on certain architectures (e.g., x86, but not x86_64) +.BR expm1 () +raised a bogus underflow floating-point exception +for some large negative +.I x +values (where the function result approaches \-1). +.P +Before approximately glibc 2.11, +.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6814 +.\" e.g., expm1(1e5) through expm1(1.00199970127e5), +.\" but not expm1(1.00199970128e5) and beyond. +.BR expm1 () +raised a bogus invalid floating-point exception in addition to the expected +overflow exception, and returned a NaN instead of positive infinity, +for some large positive +.I x +values. +.P +Before glibc 2.11, +.\" It looks like the fix was in glibc 2.11, or possibly glibc 2.12. +.\" I have no test system for glibc 2.11, but glibc 2.12 passes. +.\" From the source (sysdeps/i386/fpu/s_expm1.S) it looks +.\" like the changes were in glibc 2.11. +the glibc implementation did not set +.\" https://www.sourceware.org/bugzilla/show_bug.cgi?id=6788 +.I errno +to +.B ERANGE +when a range error occurred. +.SH SEE ALSO +.BR exp (3), +.BR log (3), +.BR log1p (3) |