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diff --git a/upstream/archlinux/man3p/ilogb.3p b/upstream/archlinux/man3p/ilogb.3p new file mode 100644 index 00000000..fe2169f9 --- /dev/null +++ b/upstream/archlinux/man3p/ilogb.3p @@ -0,0 +1,195 @@ +'\" et +.TH ILOGB "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" +.SH PROLOG +This manual page is part of the POSIX Programmer's Manual. +The Linux implementation of this interface may differ (consult +the corresponding Linux manual page for details of Linux behavior), +or the interface may not be implemented on Linux. +.\" +.EQ +delim $$ +.EN +.SH NAME +ilogb, +ilogbf, +ilogbl +\(em return an unbiased exponent +.SH SYNOPSIS +.LP +.nf +#include <math.h> +.P +int ilogb(double \fIx\fP); +int ilogbf(float \fIx\fP); +int ilogbl(long double \fIx\fP); +.fi +.SH DESCRIPTION +The functionality described on this reference page is aligned with the +ISO\ C standard. Any conflict between the requirements described here and the +ISO\ C standard is unintentional. This volume of POSIX.1\(hy2017 defers to the ISO\ C standard. +.P +These functions shall return the exponent part of their argument +.IR x . +Formally, the return value is the integral part of $log sub{r}|x|$ as a +signed integral value, for non-zero +.IR x , +where +.IR r +is the radix of the machine's floating-point arithmetic, which is the +value of FLT_RADIX defined in +.IR <float.h> . +.P +An application wishing to check for error situations should set +.IR errno +to zero and call +.IR feclearexcept (FE_ALL_EXCEPT) +before calling these functions. On return, if +.IR errno +is non-zero or \fIfetestexcept\fR(FE_INVALID | FE_DIVBYZERO | +FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred. +.SH "RETURN VALUE" +Upon successful completion, these functions shall return the exponent +part of +.IR x +as a signed integer value. They are equivalent to calling the +corresponding +\fIlogb\fR() +function and casting the returned value to type +.BR int . +.P +If +.IR x +is 0, the value FP_ILOGB0 shall be returned. +On XSI-conformant systems, a domain error shall occur; +.br +otherwise, a +domain +error may occur. +.P +If +.IR x +is \(+-Inf, the value +{INT_MAX} +shall be returned. +On XSI-conformant systems, a domain error shall occur; +.br +otherwise, a +domain +error may occur. +.P +If +.IR x +is a NaN, the value FP_ILOGBNAN shall be returned. +On XSI-conformant systems, a domain error shall occur; +.br +otherwise, a +domain +error may occur. +.P +If the correct value is greater than +{INT_MAX}, +a domain error shall occur and +an unspecified value shall be returned. +On XSI-conformant systems, a domain error shall occur and +{INT_MAX} +shall be returned. +.P +If the correct value is less than +{INT_MIN}, +a domain error shall occur and +an unspecified value shall be returned. +On XSI-conformant systems, a domain error shall occur and +{INT_MIN} +shall be returned. +.SH ERRORS +These functions shall fail if: +.IP "Domain\ Error" 12 +The correct value is not representable as an integer. +.RS 12 +.P +The +.IR x +argument is zero, NaN, or \(+-Inf. +.P +If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is +non-zero, then +.IR errno +shall be set to +.BR [EDOM] . +If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is +non-zero, then the invalid floating-point exception shall be raised. +.RE +.P +These functions may fail if: +.IP "Domain\ Error" 12 +The +.IR x +argument is zero, NaN, or \(+-Inf. +.RS 12 +.P +If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is +non-zero, then +.IR errno +shall be set to +.BR [EDOM] . +If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is +non-zero, then the invalid floating-point exception shall be raised. +.RE +.LP +.IR "The following sections are informative." +.SH EXAMPLES +None. +.SH "APPLICATION USAGE" +On error, the expressions (\fImath_errhandling\fR & MATH_ERRNO) and +(\fImath_errhandling\fR & MATH_ERREXCEPT) are independent of each +other, but at least one of them must be non-zero. +.SH RATIONALE +The errors come from taking the expected floating-point value and +converting it to +.BR int , +which is an invalid operation in IEEE\ Std\ 754\(hy1985 (since overflow, infinity, and +NaN are not representable in a type +.BR int ), +so should be a domain error. +.P +There are no known implementations that overflow. For overflow to +happen, +{INT_MAX} +must be less than LDBL_MAX_EXP*\fIlog2\fP(FLT_RADIX) or +{INT_MIN} +must be greater than LDBL_MIN_EXP*\fIlog2\fP(FLT_RADIX) if subnormals +are not supported, or +{INT_MIN} +must be greater than (LDBL_MIN_EXP-LDBL_MANT_DIG)*\fIlog2\fP(FLT_RADIX) +if subnormals are supported. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "\fIfeclearexcept\fR\^(\|)", +.IR "\fIfetestexcept\fR\^(\|)", +.IR "\fIlogb\fR\^(\|)", +.IR "\fIscalbln\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2017, +.IR "Section 4.20" ", " "Treatment of Error Conditions for Mathematical Functions", +.IR "\fB<float.h>\fP", +.IR "\fB<math.h>\fP" +.\" +.SH COPYRIGHT +Portions of this text are reprinted and reproduced in electronic form +from IEEE Std 1003.1-2017, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, 2018 Edition, +Copyright (C) 2018 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +In the event of any discrepancy between this version and the original IEEE and +The Open Group Standard, the original IEEE and The Open Group Standard +is the referee document. The original Standard can be obtained online at +http://www.opengroup.org/unix/online.html . +.PP +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |