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diff --git a/man-pages-posix-2017/man3p/pow.3p b/man-pages-posix-2017/man3p/pow.3p new file mode 100644 index 0000000..1e28125 --- /dev/null +++ b/man-pages-posix-2017/man3p/pow.3p @@ -0,0 +1,317 @@ +'\" et +.TH POW "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. +.\" +.SH NAME +pow, +powf, +powl +\(em power function +.SH SYNOPSIS +.LP +.nf +#include <math.h> +.P +double pow(double \fIx\fP, double \fIy\fP); +float powf(float \fIx\fP, float \fIy\fP); +long double powl(long double \fIx\fP, long double \fIy\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 compute the value of +.IR x +raised to the power +.IR y , +.IR x\u\s-3y\s+3\d . +If +.IR x +is negative, the application shall ensure that +.IR y +is an integer value. +.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 value of +.IR x +raised to the power +.IR y . +.P +For finite values of +.IR x +< 0, and finite non-integer values of +.IR y , +a domain error shall occur and +either a NaN (if representable), or +an implementation-defined value shall be returned. +.P +If the correct value would cause overflow, a range error shall occur +and +\fIpow\fR(), +\fIpowf\fR(), +and +\fIpowl\fR() +shall return \(+-HUGE_VAL, \(+-HUGE_VALF, and \(+-HUGE_VALL, +respectively, with the same sign as the correct value of the function. +.P +If the correct value would cause underflow, +and is not representable, +a range error may occur, and +\fIpow\fR(), +\fIpowf\fR(), +and +\fIpowl\fR() +shall return +0.0, or +(if IEC 60559 Floating-Point is not supported) an implementation-defined +value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, +respectively. +.P +For +.IR y +< 0, if +.IR x +is zero, a +pole +error may occur and +\fIpow\fR(), +\fIpowf\fR(), +and +\fIpowl\fR() +shall return \(+-HUGE_VAL, \(+-HUGE_VALF, and \(+-HUGE_VALL, respectively. +On systems that support the IEC 60559 Floating-Point option, if +.IR x +is \(+-0, a pole error shall occur and +\fIpow\fR(), +\fIpowf\fR(), +and +\fIpowl\fR() +shall return \(+-HUGE_VAL, \(+-HUGE_VALF, and \(+-HUGE_VALL, respectively +if +.IR y +is an odd integer, or HUGE_VAL, HUGE_VALF, and HUGE_VALL, respectively if +.IR y +is not an odd integer. +.P +If +.IR x +or +.IR y +is a NaN, a NaN shall be returned (unless specified elsewhere in this +description). +.P +For any value of +.IR y +(including NaN), if +.IR x +is +1, 1.0 shall be returned. +.P +For any value of +.IR x +(including NaN), if +.IR y +is \(+-0, 1.0 shall be returned. +.P +For any odd integer value of +.IR y +> 0, if +.IR x +is \(+-0, \(+-0 shall be returned. +.P +For +.IR y +> 0 and not an odd integer, if +.IR x +is \(+-0, +0 shall be returned. +.P +If +.IR x +is \-1, and +.IR y +is \(+-Inf, 1.0 shall be returned. +.P +For |\fIx\fP| < 1, if +.IR y +is \-Inf, +Inf shall be returned. +.P +For |\fIx\fP| > 1, if +.IR y +is \-Inf, +0 shall be returned. +.P +For |\fIx\fP| < 1, if +.IR y +is +Inf, +0 shall be returned. +.P +For |\fIx\fP| > 1, if +.IR y +is +Inf, +Inf shall be returned. +.P +For +.IR y +an odd integer < 0, if +.IR x +is \-Inf, \-0 shall be returned. +.P +For +.IR y +< 0 and not an odd integer, if +.IR x +is \-Inf, +0 shall be returned. +.P +For +.IR y +an odd integer > 0, if +.IR x +is \-Inf, \-Inf shall be returned. +.P +For +.IR y +> 0 and not an odd integer, if +.IR x +is \-Inf, +Inf shall be returned. +.P +For +.IR y +< 0, if +.IR x +is +Inf, +0 shall be returned. +.P +For +.IR y +> 0, if +.IR x +is +Inf, +Inf shall be returned. +.P +If the correct value would cause underflow, and is representable, a +range error may occur and the correct value shall be returned. +.SH ERRORS +These functions shall fail if: +.IP "Domain\ Error" 12 +The value of +.IR x +is negative and +.IR y +is a finite non-integer. +.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 +.IP "Pole\ Error" 12 +The value of +.IR x +is zero and +.IR y +is negative. +.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 +.IP "Range\ Error" 12 +The result overflows. +.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 overflow floating-point exception shall be raised. +.RE +.P +These functions may fail if: +.IP "Pole\ Error" 12 +The value of +.IR x +is zero and +.IR y +is negative. +.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 +.IP "Range\ Error" 12 +The result underflows. +.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 underflow 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 "\fIexp\fR\^(\|)", +.IR "\fIfeclearexcept\fR\^(\|)", +.IR "\fIfetestexcept\fR\^(\|)", +.IR "\fIisnan\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2017, +.IR "Section 4.20" ", " "Treatment of Error Conditions for Mathematical Functions", +.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 . |