nexttoward(3m)

1nextafter(3M)           Mathematical Library Functions           nextafter(3M)
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NAME

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

10       c99 [ flag... ] file... -lm [ library... ]
11       #include <math.h>
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13       double nextafter(double x, double y);
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16       float nextafterf(float x, float y);
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19       long double nextafterl(long double x, long double y);
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22       double nexttoward(double x, long double y);
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25       float nexttowardf(float x, long double y);
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28       long double nexttowardl(long double x, long double y);
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DESCRIPTION

32       The nextafter(), nextafterf(), and nextafterl() functions  compute  the
33       next representable floating-point value following x in the direction of
34       y. Thus, if y is less than x, nextafter() returns  the  largest  repre‐
35       sentable   floating-point   number   less   than  x.  The  nextafter(),
36       nextafterf(), and nextafterl() functions return y if x equals y.
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39       The nexttoward(), nexttowardf(), and nexttowardl() functions are equiv‐
40       alent  to the corresponding nextafter() functions, except that the sec‐
41       ond parameter has type long double and the functions return y converted
42       to the type of the function if x equals y.
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RETURN VALUES

45       Upon  successful  completion,  these  functions  return the next repre‐
46       sentable floating-point value following x in the direction of y.
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49       If x == y, y (of the type x) is returned.
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52       If x is finite and the correct function value would overflow,  a  range
53       error  occurs  and ±HUGE_VAL, ±HUGE_VALF, and ±HUGE_VALL (with the same
54       sign as x) is returned as appropriate for the return type of the  func‐
55       tion.
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58       If x or y is NaN, a NaN is returned.
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61       If  x != y and the correct function value is subnormal, zero, or under‐
62       flows, a range error occurs and either the correct function  value  (if
63       representable) or 0.0 is returned.
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ERRORS

66       These functions will fail if:
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68       Range Error    The correct value overflows.
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70                      If    the   integer   expression   (math_errhandling   &
71                      MATH_ERREXCEPT) is non-zero, the overflow floating-point
72                      exception is raised.
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74                      The  nextafter()  function  sets  errno to ERANGE if the
75                      correct value would overflow.
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78       Range Error    The correct value underflows.
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80                      If   the   integer   expression   (math_errhandling    &
81                      MATH_ERREXCEPT)  is  non-zero,  the  underflow floating-
82                      point exception is raised.
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USAGE

86       An application wanting to check for exceptions should  call  feclearex‐
87       cept(FE_ALL_EXCEPT)  before  calling  these  functions.  On  return, if
88       fetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is
89       non-zero,  an  exception  has been raised. An application should either
90       examine the return value or check the floating point exception flags to
91       detect exceptions.
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94       An  application  can also set errno to 0 before calling nextafter(). On
95       return, if errno is non-zero, an error has occurred. The  nextafterf(),
96       nextafterl().  nexttoward(), nexttowardf(), and nexttowardl() functions
97       do not set errno.
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ATTRIBUTES

100       See attributes(5) for descriptions of the following attributes:
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105       ┌─────────────────────────────┬─────────────────────────────┐
106       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
107       ├─────────────────────────────┼─────────────────────────────┤
108       │Interface Stability          │Standard                     │
109       ├─────────────────────────────┼─────────────────────────────┤
110       │MT-Level                     │MT-Safe                      │
111       └─────────────────────────────┴─────────────────────────────┘
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