NEXTAFTER(3M) | Mathematical Library Functions | NEXTAFTER(3M) |

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

c99 [flag... ]file...-lm[library... ] #include <math.h>doublenextafter(doublex,doubley);

floatnextafterf(floatx,floaty);

long doublenextafterl(long doublex,long doubley);

doublenexttoward(doublex,long doubley);

floatnexttowardf(floatx,long doubley);

long doublenexttowardl(long doublex,long doubley);

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

The **nexttoward()**, **nexttowardf()**, and
**nexttowardl()** functions are equivalent to the corresponding
**nextafter()** functions, except that the second parameter has type
**long double** and the functions return *y* converted to the type
of the function if *x* equals *y*.

Upon successful completion, these functions return the next
representable floating-point value following *x* in the direction of
*y*.

If *x* == *y*, *y* (of the type *x*) is
returned.

If *x* is finite and the correct function value would
overflow, a range error occurs and ±**HUGE_VAL**,
±**HUGE_VALF**, and ±**HUGE_VALL** (with the same sign
as *x*) is returned as appropriate for the return type of the
function.

If *x* or *y* is NaN, a NaN is returned.

If *x* != *y* and the correct function value is
subnormal, zero, or underflows, a range error occurs and either the correct
function value (if representable) or 0.0 is returned.

These functions will fail if:

**Range Error**

The correct value overflows.

If the integer expression (**math_errhandling** &
**MATH_ERREXCEPT**) is non-zero, the overflow floating-point exception is
raised.

The **nextafter()** function sets **errno** to **ERANGE**
if the correct value would overflow.

**Range Error**

The correct value underflows.

If the integer expression (**math_errhandling** &
**MATH_ERREXCEPT**) is non-zero, the underflow floating-point exception
is raised.

An application wanting to check for exceptions should call
**feclearexcept**(**FE_ALL_EXCEPT**) before calling these functions.
On return, if **fetestexcept**(**FE_INVALID** | **FE_DIVBYZERO** |
**FE_OVERFLOW** | **FE_UNDERFLOW**) is non-zero, an exception has been
raised. An application should either examine the return value or check the
floating point exception flags to detect exceptions.

An application can also set **errno** to 0 before calling
**nextafter()**. On return, if **errno** is non-zero, an error has
occurred. The **nextafterf()**, **nextafterl()**. **nexttoward()**,
**nexttowardf()**, and **nexttowardl()** functions do not set
**errno**.

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE | ATTRIBUTE VALUE |

Interface Stability | Standard |

MT-Level | MT-Safe |

math.h(3HEAD), feclearexcept(3M), fetestexcept(3M), attributes(7), standards(7)

July 12, 2006 | SunOS 5.11 |