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

6       erf, erff, erfl - error function
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SYNOPSIS

9       #include <math.h>
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11       double erf(double x);
12       float erff(float x);
13       long double erfl(long double x);
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15       Link with -lm.
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       erf():
20           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
21               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
22               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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24       erff(), erfl():
25           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
26               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
27               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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DESCRIPTION

30       These functions return the error function of x, defined as
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32           erf(x) = 2/sqrt(pi) * integral from 0 to x of exp(-t*t) dt
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RETURN VALUE

35       On  success,  these functions return the value of the error function of
36       x, a value in the range [-1, 1].
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38       If x is a NaN, a NaN is returned.
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40       If x is +0 (-0), +0 (-0) is returned.
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42       If x is positive infinity (negative infinity), +1 (-1) is returned.
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44       If x is subnormal, a range  error  occurs,  and  the  return  value  is
45       2*x/sqrt(pi).
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ERRORS

48       See  math_error(7) for information on how to determine whether an error
49       has occurred when calling these functions.
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51       The following errors can occur:
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53       Range error: result underflow (x is subnormal)
54              An underflow floating-point exception (FE_UNDERFLOW) is raised.
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56       These functions do not set errno.
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ATTRIBUTES

59       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
60       tributes(7).
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62       ┌────────────────────────────────────────────┬───────────────┬─────────┐
63       │Interface                                   │ Attribute     │ Value   │
64       ├────────────────────────────────────────────┼───────────────┼─────────┤
65       │erf(), erff(), erfl()                       │ Thread safety │ MT-Safe │
66       └────────────────────────────────────────────┴───────────────┴─────────┘
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CONFORMING TO

69       C99, POSIX.1-2001, POSIX.1-2008.
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71       The variant returning double also conforms to SVr4, 4.3BSD.
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SEE ALSO

74       cerf(3), erfc(3), exp(3)
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COLOPHON

77       This  page  is  part of release 5.13 of the Linux man-pages project.  A
78       description of the project, information about reporting bugs,  and  the
79       latest     version     of     this    page,    can    be    found    at
80       https://www.kernel.org/doc/man-pages/.
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84GNU                               2021-03-22                            ERF(3)
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