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scalbln(3p) — Linux manual page

SCALBLN(3P)             POSIX Programmer's ManualSCALBLN(3P)

PROLOG        top

       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.

NAME        top

       scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl — compute       exponent using FLT_RADIX

SYNOPSIS        top

       #include <math.h>       double scalbln(doublex, longn);       float scalblnf(floatx, longn);       long double scalblnl(long doublex, longn);       double scalbn(doublex, intn);       float scalbnf(floatx, intn);       long double scalbnl(long doublex, intn);

DESCRIPTION        top

       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.1‐2017 defers to the ISO C standard.       These functions shall computex * FLT_RADIXn efficiently, not       normally by computing FLT_RADIXn explicitly.       An application wishing to check for error situations should seterrno to zero and callfeclearexcept(FE_ALL_EXCEPT) before calling       these functions. On return, iferrno is non-zero orfetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW |       FE_UNDERFLOW) is non-zero, an error has occurred.

RETURN VALUE        top

       Upon successful completion, these functions shall returnx * FLT_RADIXn.       If the result would cause overflow, a range error shall occur and       these functions shall return ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL       (according to the sign ofx) as appropriate for the return type of       the function.       If the correct value would cause underflow, and is not       representable, a range error may occur, andscalbln(),scalblnf(),scalblnl(),scalbn(),scalbnf(), andscalbnl() 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, LDBL_MIN, DBL_MIN, FLT_MIN, and LDBL_MIN, respectively.       Ifx is NaN, a NaN shall be returned.       Ifx is ±0 or ±Inf,x shall be returned.       Ifn is 0,x shall be returned.       If the correct value would cause underflow, and is representable,       a range error may occur and the correct value shall be returned.

ERRORS        top

       These functions shall fail if:       Range Error The result overflows.                   If the integer expression (math_errhandling &                   MATH_ERRNO) is non-zero, thenerrno shall be set to[ERANGE].  If the integer expression (math_errhandling                   & MATH_ERREXCEPT) is non-zero, then the overflow                   floating-point exception shall be raised.       These functions may fail if:       Range Error The result underflows.                   If the integer expression (math_errhandling &                   MATH_ERRNO) is non-zero, thenerrno shall be set to[ERANGE].  If the integer expression (math_errhandling                   & MATH_ERREXCEPT) is non-zero, then the underflow                   floating-point exception shall be raised.The following sections are informative.

EXAMPLES        top

       None.

APPLICATION USAGE        top

       On error, the expressions (math_errhandling & MATH_ERRNO) and       (math_errhandling & MATH_ERREXCEPT) are independent of each other,       but at least one of them must be non-zero.

RATIONALE        top

       These functions are named so as to avoid conflicting with the       historical definition of thescalb() function from the Single UNIX       Specification. The difference is that thescalb() function has a       second argument ofdoubleinstead ofint.  Thescalb() function is       not part of the ISO C standard. The three functions whose second       type islongare provided because the factor required to scale       from the smallest positive floating-point value to the largest       finite one, on many implementations, is too large to represent in       the minimum-widthintformat.

FUTURE DIRECTIONS        top

       None.

SEE ALSO        top

feclearexcept(3p),fetestexcept(3p)       The Base Definitions volume of POSIX.1‐2017,Section 4.20,Treatment of Error Conditions for Mathematical Functions,math.h(0p)

COPYRIGHT        top

       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 athttp://www.opengroup.org/unix/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, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017SCALBLN(3P)

Pages that refer to this page:math.h(0p), ilogb(3p), logb(3p)

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