SCALBLN(3)                 POSIX Programmer's Manual                SCALBLN(3)



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NNAAMMEE
       scalbln, scalblnf, scalblnl, scalbn, scalbnf, scalbnl -- compute
       exponent using FLT_RADIX

SSYYNNOOPPSSIISS
       #include <math.h>

       double scalbln(double _x, long _n);
       float scalblnf(float _x, long _n);
       long double scalblnl(long double _x, long _n);
       double scalbn(double _x, int _n);
       float scalbnf(float _x, int _n);
       long double scalbnl(long double _x, int _n);

DDEESSCCRRIIPPTTIIOONN
       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 compute _x * FLT_RADIX_n efficiently, not normally
       by computing FLT_RADIX_n explicitly.

       An application wishing to check for error situations should set _e_r_r_n_o
       to zero and call _f_e_c_l_e_a_r_e_x_c_e_p_t(FE_ALL_EXCEPT) before calling these
       functions. On return, if _e_r_r_n_o is non-zero or _f_e_t_e_s_t_e_x_c_e_p_t(FE_INVALID |
       FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
       occurred.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, these functions shall return
       _x * FLT_RADIX_n.

       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 of _x) 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, and _s_c_a_l_b_l_n(), _s_c_a_l_b_l_n_f(), _s_c_a_l_b_l_n_l(), _s_c_a_l_b_n(),
       _s_c_a_l_b_n_f(), and _s_c_a_l_b_n_l() 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.

       If _x is NaN, a NaN shall be returned.

       If _x is +-0 or +-Inf, _x shall be returned.

       If _n 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.

EERRRROORRSS
       These functions shall fail if:

       Range Error The result overflows.

                   If the integer expression (_m_a_t_h___e_r_r_h_a_n_d_l_i_n_g & MATH_ERRNO)
                   is non-zero, then _e_r_r_n_o shall be set to [[EERRAANNGGEE]].  If the
                   integer expression (_m_a_t_h___e_r_r_h_a_n_d_l_i_n_g & 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 (_m_a_t_h___e_r_r_h_a_n_d_l_i_n_g & MATH_ERRNO)
                   is non-zero, then _e_r_r_n_o shall be set to [[EERRAANNGGEE]].  If the
                   integer expression (_m_a_t_h___e_r_r_h_a_n_d_l_i_n_g & MATH_ERREXCEPT) is
                   non-zero, then the underflow floating-point exception shall
                   be raised.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

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

RRAATTIIOONNAALLEE
       These functions are named so as to avoid conflicting with the
       historical definition of the _s_c_a_l_b() function from the Single UNIX
       Specification. The difference is that the _s_c_a_l_b() function has a second
       argument of ddoouubbllee instead of iinntt.  The _s_c_a_l_b() function is not part of
       the ISO C standard. The three functions whose second type is lloonngg are
       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-width iinntt
       format.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _f_e_c_l_e_a_r_e_x_c_e_p_t(), _f_e_t_e_s_t_e_x_c_e_p_t()

       The Base Definitions volume of POSIX.1-2017, _S_e_c_t_i_o_n _4_._2_0, _T_r_e_a_t_m_e_n_t _o_f
       _E_r_r_o_r _C_o_n_d_i_t_i_o_n_s _f_o_r _M_a_t_h_e_m_a_t_i_c_a_l _F_u_n_c_t_i_o_n_s, <<mmaatthh..hh>>

CCOOPPYYRRIIGGHHTT
       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 .

       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 .



IEEE/The Open Group                  2017                           SCALBLN(3)
