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diff --git a/man-pages-posix-2013/man3p/logb.3p b/man-pages-posix-2013/man3p/logb.3p new file mode 100644 index 0000000..1f26022 --- /dev/null +++ b/man-pages-posix-2013/man3p/logb.3p @@ -0,0 +1,163 @@ +'\" et +.TH LOGB "3P" 2013 "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. + +.SH NAME +logb, +logbf, +logbl +\(em radix-independent exponent +.SH SYNOPSIS +.LP +.nf +#include <math.h> +.P +double logb(double \fIx\fP); +float logbf(float \fIx\fP); +long double logbl(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\(hy2008 defers to the ISO\ C standard. +.P +These functions shall compute the exponent of +.IR x , +which is the integral part of log\fI\d\s-3r\s+3\u\fR +|\|\fIx\fR\||, as a signed floating-point 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 the +.IR <float.h> +header. +.P +If +.IR x +is subnormal it is treated as though it were normalized; thus for +finite positive +.IR x : +.sp +.RS 4 +.nf +\fB +1 <= \fIx\fP * FLT_RADIX\s-3\u\(milogb(x)\d\s+3 < FLT_RADIX +.fi \fR +.P +.RE +.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 +of +.IR x . +.P +If +.IR x +is \(+-0, +\fIlogb\fR(), +\fIlogbf\fR(), +and +\fIlogbl\fR() +shall return \(miHUGE_VAL, \(miHUGE_VALF, and \(miHUGE_VALL, +respectively. +.P +On systems that support the IEC 60559 Floating-Point option, a pole +error shall occur; +.br +otherwise, a +pole +error may occur. +.P +If +.IR x +is NaN, a NaN shall be returned. +.P +If +.IR x +is \(+-Inf, +Inf shall be returned. +.SH ERRORS +These functions shall fail if: +.IP "Pole\ Error" 12 +The value of +.IR x +is \(+-0. +.RS 12 +.P +If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is +non-zero, then +.IR errno +shall be set to +.BR [ERANGE] . +If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is +non-zero, then the divide-by-zero floating-point exception shall be +raised. +.RE +.P +These functions may fail if: +.IP "Pole\ Error" 12 +The value of +.IR x +is 0. +.RS 12 +.P +If the integer expression (\fImath_errhandling\fR & MATH_ERRNO) is +non-zero, then +.IR errno +shall be set to +.BR [ERANGE] . +If the integer expression (\fImath_errhandling\fR & MATH_ERREXCEPT) is +non-zero, then the divide-by-zero 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 +None. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "\fIfeclearexcept\fR\^(\|)", +.IR "\fIfetestexcept\fR\^(\|)", +.IR "\fIilogb\fR\^(\|)", +.IR "\fIscalbln\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2008, +.IR "Section 4.19" ", " "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, 2013 Edition, Standard for Information Technology +-- Portable Operating System Interface (POSIX), The Open Group Base +Specifications Issue 7, Copyright (C) 2013 by the Institute of +Electrical and Electronics Engineers, Inc and The Open Group. +(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html . + +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 . |