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Diffstat (limited to 'man/man3/ilogb.3')
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diff --git a/man/man3/ilogb.3 b/man/man3/ilogb.3 new file mode 100644 index 000000000..5130e40e0 --- /dev/null +++ b/man/man3/ilogb.3 @@ -0,0 +1,150 @@ +'\" t +.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>. +.\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" Inspired by a page by Walter Harms created 2002-08-10 +.\" +.TH ilogb 3 (date) "Linux man-pages (unreleased)" +.SH NAME +ilogb, ilogbf, ilogbl \- get integer exponent of a floating-point value +.SH LIBRARY +Math library +.RI ( libm ", " \-lm ) +.SH SYNOPSIS +.nf +.B #include <math.h> +.P +.BI "int ilogb(double " x ); +.BI "int ilogbf(float " x ); +.BI "int ilogbl(long double " x ); +.fi +.P +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.P +.BR ilogb (): +.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 ilogbf (), +.BR ilogbl (): +.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 exponent part of their argument +as a signed integer. +When no error occurs, these functions +are equivalent to the corresponding +.BR logb (3) +functions, cast to +.IR int . +.SH RETURN VALUE +On success, these functions return the exponent of +.IR x , +as a signed integer. +.P +If +.I x +is zero, then a domain error occurs, and the functions return +.\" the POSIX.1 spec for logb() says logb() gives pole error for this +.\" case, but for ilogb() it says domain error. +.BR FP_ILOGB0 . +.\" glibc: The numeric value is either `INT_MIN' or `-INT_MAX'. +.P +If +.I x +is a NaN, then a domain error occurs, and the functions return +.BR FP_ILOGBNAN . +.\" glibc: The numeric value is either `INT_MIN' or `INT_MAX'. +.\" On i386, FP_ILOGB0 and FP_ILOGBNAN have the same value. +.P +If +.I x +is negative infinity or positive infinity, then +a domain error occurs, and the functions return +.BR INT_MAX . +.\" +.\" POSIX.1-2001 also says: +.\" If the correct value is greater than {INT_MAX}, {INT_MAX} +.\" shall be returned and a domain error shall occur. +.\" +.\" If the correct value is less than {INT_MIN}, {INT_MIN} +.\" shall be returned and a domain error shall occur. +.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 0 or a NaN +An invalid floating-point exception +.RB ( FE_INVALID ) +is raised, and +.I errno +is set to +.B EDOM +(but see BUGS). +.TP +Domain error: \fIx\fP is an infinity +An invalid floating-point exception +.RB ( FE_INVALID ) +is raised, and +.I errno +is set to +.B EDOM +(but see BUGS). +.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 ilogb (), +.BR ilogbf (), +.BR ilogbl () +T} Thread safety MT-Safe +.TE +.SH STANDARDS +C11, POSIX.1-2008. +.SH HISTORY +C99, POSIX.1-2001. +.SH BUGS +.\" Bug raised: https://www.sourceware.org/bugzilla/show_bug.cgi?id=6794 +Before glibc 2.16, the following bugs existed in the +glibc implementation of these functions: +.IP \[bu] 3 +The domain error case where +.I x +is 0 or a NaN did not cause +.I errno +to be set or (on some architectures) raise a floating-point exception. +.IP \[bu] +The domain error case where +.I x +is an infinity did not cause +.I errno +to be set or raise a floating-point exception. +.SH SEE ALSO +.BR log (3), +.BR logb (3), +.BR significand (3) |