NEXTAFTER(3)               POSIX Programmer's Manual              NEXTAFTER(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
       nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl
       -- next representable floating-point number

SSYYNNOOPPSSIISS
       #include <math.h>

       double nextafter(double _x, double _y);
       float nextafterf(float _x, float _y);
       long double nextafterl(long double _x, long double _y);
       double nexttoward(double _x, long double _y);
       float nexttowardf(float _x, long double _y);
       long double nexttowardl(long double _x, long double _y);

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.

       The _n_e_x_t_a_f_t_e_r(), _n_e_x_t_a_f_t_e_r_f(), and _n_e_x_t_a_f_t_e_r_l() functions shall compute
       the next representable floating-point value following _x in the
       direction of _y.  Thus, if _y is less than _x, _n_e_x_t_a_f_t_e_r() shall return
       the largest representable floating-point number less than _x.  The
       _n_e_x_t_a_f_t_e_r(), _n_e_x_t_a_f_t_e_r_f(), and _n_e_x_t_a_f_t_e_r_l() functions shall return _y if
       _x equals _y.

       The _n_e_x_t_t_o_w_a_r_d(), _n_e_x_t_t_o_w_a_r_d_f(), and _n_e_x_t_t_o_w_a_r_d_l() functions shall be
       equivalent to the corresponding _n_e_x_t_a_f_t_e_r() functions, except that the
       second parameter shall have type lloonngg ddoouubbllee and the functions shall
       return _y converted to the type of the function if _x equals _y.

       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 the next
       representable floating-point value following _x in the direction of _y.

       If _x==_y, _y (of the type _x) shall be returned.

       If _x is finite and the correct function value would overflow, a range
       error shall occur and +-HUGE_VAL, +-HUGE_VALF, and +-HUGE_VALL (with
       the same sign as _x) shall be returned as appropriate for the return
       type of the function.

       If _x or _y is NaN, a NaN shall be returned.

       If _x!=_y and the correct function value is subnormal, zero, or
       underflows, a range error shall occur, and
       the correct function value (if representable) or
       0.0 shall be returned.

EERRRROORRSS
       These functions shall fail if:

       Range Error The correct value 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.

       Range Error The correct value is subnormal or 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.

       When _<_t_g_m_a_t_h_._h_> is included, note that the return type of _n_e_x_t_a_f_t_e_r()
       depends on the generic typing deduced from both arguments, while the
       return type of _n_e_x_t_t_o_w_a_r_d() depends only on the generic typing of the
       first argument.

RRAATTIIOONNAALLEE
       None.

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>>, <<ttggmmaatthh..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                         NEXTAFTER(3)
