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nextafterf (3)
  • nextafterf (3) ( FreeBSD man: Библиотечные вызовы )
  • nextafterf (3) ( Русские man: Библиотечные вызовы )
  • nextafterf (3) ( Linux man: Библиотечные вызовы )
  • >> nextafterf (3) ( POSIX man: Библиотечные вызовы )
  •  

    NAME

    nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl
    - next representable floating-point
    number
     
    

    SYNOPSIS

    #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);
     

    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 IEEE Std 1003.1-2001 defers to the ISO C standard.

    The nextafter(), nextafterf(), and nextafterl() functions shall compute the next representable floating-point value following x in the direction of y. Thus, if y is less than x, nextafter() shall return the largest representable floating-point number less than x. The nextafter(), nextafterf(), and nextafterl() functions shall return y if x equals y.

    The nexttoward(), nexttowardf(), and nexttowardl() functions shall be equivalent to the corresponding nextafter() functions, except that the second parameter shall have type long double 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 errno to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, if errno is non-zero or fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred.  

    RETURN VALUE

    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 either the correct function value (if representable) or 0.0 shall be returned.  

    ERRORS

    These functions shall fail if:

    Range Error
    The correct value overflows.

    If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno 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.

    Range Error
    The correct value is subnormal or underflows.

    If the integer expression (math_errhandling & MATH_ERRNO) is non-zero, then errno 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

    None.  

    APPLICATION USAGE

    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

    None.  

    FUTURE DIRECTIONS

    None.  

    SEE ALSO

    feclearexcept() , fetestexcept() , the Base Definitions volume of IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions for Mathematical Functions, <math.h>  

    COPYRIGHT

    Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    RETURN VALUE
    ERRORS
    EXAMPLES
    APPLICATION USAGE
    RATIONALE
    FUTURE DIRECTIONS
    SEE ALSO
    COPYRIGHT


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