mirror of https://github.com/mkerrisk/man-pages
103 lines
2.8 KiB
Groff
103 lines
2.8 KiB
Groff
.\" Copyright 2004 Andries Brouwer <aeb@cwi.nl>.
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" Inspired by a page by Walter Harms created 2002-08-10
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.\"
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.TH ILOGB 3 2004-10-31 "" "Linux Programmer's Manual"
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.SH NAME
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ilogb, ilogbf, ilogbl \- get integer exponent of a floating point value
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.SH SYNOPSIS
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.B #include <math.h>
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.sp
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.BI "int ilogb(double " x );
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.br
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.BI "int ilogbf(float " x );
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.br
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.BI "int ilogbl(long double " x );
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.sp
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Link with \fI\-lm\fP.
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.SH DESCRIPTION
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These functions return the exponent part of their argument
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as a signed integer.
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When no error occurs, these functions
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are equivalent to the corresponding
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.BR logb (3)
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functions, cast to
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.IR (int) .
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An error will occur for zero and infinity and NaN,
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and possibly for overflow.
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.\" .SH "RETURN VALUE"
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.\" These functions return the exponent part of their argument
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.\" as a signed integer.
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.SH ERRORS
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In order to check for errors, set
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.I errno
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to zero and call
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.I feclearexcept(FE_ALL_EXCEPT)
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before calling these functions.
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On return, if
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.I errno
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is nonzero or
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.I fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW)
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is nonzero, an error has occurred.
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.LP
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If an error occurs and
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.I "(math_errhandling & MATH_ERRNO)"
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is nonzero, then
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.I errno
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is set to
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.BR EDOM .
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If an error occurs and
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.I "(math_errhandling & MATH_ERREXCEPT)"
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is nonzero, then the invalid floating-point exception is raised.
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.LP
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A domain error occurs when
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.I x
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is zero or infinite (or too large, or too small) or NaN.
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If
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.I x
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is zero, the constant
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.B FP_ILOGB0
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is returned.
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.\" glibc: The numeric value is either `INT_MIN' or `-INT_MAX'.
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If
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.I x
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is NaN, the constant
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.B FP_ILOGBNAN
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is returned.
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.\" glibc: The numeric value is either `INT_MIN' or `INT_MAX'.
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If
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.I x
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is infinite (or too large),
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.B INT_MAX
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is returned.
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If
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.I x
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is too small,
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.B INT_MIN
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is returned.
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.SH "CONFORMING TO"
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C99
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.SH "SEE ALSO"
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.BR log (3),
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.BR logb (3)
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