1NEXTAFTER(3)               Linux Programmer's Manual              NEXTAFTER(3)
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NAME

6       nextafter, nextafterf, nextafterl, nexttoward, nexttowardf, nexttowardl
7       - floating-point number manipulation
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SYNOPSIS

10       #include <math.h>
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12       double nextafter(double x, double y);
13       float nextafterf(float x, float y);
14       long double nextafterl(long double x, long double y);
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16       double nexttoward(double x, long double y);
17       float nexttowardf(float x, long double y);
18       long double nexttowardl(long double x, long double y);
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20       Link with -lm.
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22   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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24       nextafter(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
25       _ISOC99_SOURCE; or cc -std=c99
26       nextafterf(), nextafterl(): _BSD_SOURCE || _SVID_SOURCE ||
27       _XOPEN_SOURCE >= 600 || _ISOC99_SOURCE; or cc -std=c99
28       nexttoward(), nexttowardf(), nexttowardl(): _XOPEN_SOURCE >= 600 ||
29       _ISOC99_SOURCE; cc -std=c99
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DESCRIPTION

32       The  nextafter() functions return the next representable floating-point
33       value following x in the direction of y.  If y is less  than  x,  these
34       functions will return the largest representable number less than y.
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36       If x equals y, the functions return y.
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38       The  nexttoward()  functions  do the same as the nextafter() functions,
39       except that they have a long double second argument.
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RETURN VALUE

42       On success, these functions return  the  next  representable  floating-
43       point value after x in the direction of y.
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45       If x equals y, then y (cast to the same type as x) is returned.
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47       If x or y is a NaN, a NaN is returned.
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49       If  x  is  finite, and the result would overflow, a range error occurs,
50       and the functions return HUGE_VAL,  HUGE_VALF,  or  HUGE_VALL,  respec‐
51       tively, with the correct mathematical sign.
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53       If  x  is not equal to y, and the correct function result would be sub‐
54       normal, zero, or underflow, a range error occurs, and either  the  cor‐
55       rect value (if it can be represented), or 0.0, is returned.
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ERRORS

58       See  math_error(7) for information on how to determine whether an error
59       has occurred when calling these functions.
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61       The following errors can occur:
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63       Range error: result overflow
64              An overflow floating-point exception (FE_OVERFLOW) is raised.
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66       Range error: result is subnormal or underflows
67              An underflow floating-point exception (FE_UNDERFLOW) is raised.
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69       These functions do not set errno.
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CONFORMING TO

72       C99, POSIX.1-2001.  This function is defined in IEC 559 (and the appen‐
73       dix with recommended functions in IEEE 754/IEEE 854).
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BUGS

76       In  glibc  version  2.5  and  earlier,  these functions do not raise an
77       underflow floating-point (FE_UNDERFLOW)  exception  when  an  underflow
78       occurs.
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SEE ALSO

81       nearbyint(3)
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COLOPHON

84       This  page  is  part of release 3.22 of the Linux man-pages project.  A
85       description of the project, and information about reporting  bugs,  can
86       be found at http://www.kernel.org/doc/man-pages/.
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90GNU                               2008-10-06                      NEXTAFTER(3)
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