## Linux and UNIX Man Pages

Test Your Knowledge in Computers #794
Difficulty: Medium
1/10 has a finite binary representation.
True or False?

# nexttoward(3m) [opensolaris man page]

```nextafter(3M)						  Mathematical Library Functions					     nextafter(3M)

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

SYNOPSIS
c99 [ flag... ] file... -lm [ library... ]
#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  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.

RETURN VALUES
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.

ERRORS
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.

USAGE
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.

ATTRIBUTES
See attributes(5) for descriptions of the following attributes:

+-----------------------------+-----------------------------+
|      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
+-----------------------------+-----------------------------+
|Interface Stability	     |Standard			   |
+-----------------------------+-----------------------------+
|MT-Level		     |MT-Safe			   |
+-----------------------------+-----------------------------+