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

6       erfc, erfcf, erfcl - complementary error function
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SYNOPSIS

9       #include <math.h>
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11       double erfc(double x);
12       float erfcf(float x);
13       long double erfcl(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       erfc():
20           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE
21               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
22               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
23       erfcf(), erfcl():
24           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
25               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
26               || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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DESCRIPTION

29       These  functions return the complementary error function of x, that is,
30       1.0 - erf(x).
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RETURN VALUE

33       On success, these functions return the complementary error function  of
34       x, a value in the range [0,2].
35
36       If x is a NaN, a NaN is returned.
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38       If x is +0 or -0, 1 is returned.
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40       If x is positive infinity, +0 is returned.
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42       If x is negative infinity, +2 is returned.
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44       If  the  function  result  underflows  and  produces an unrepresentable
45       value, the return value is 0.0.
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47       If the function result underflows but produces a  representable  (i.e.,
48       subnormal) value, that value is returned, and a range error occurs.
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ERRORS

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

62       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
63       tributes(7).
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65       ┌─────────────────────────┬───────────────┬─────────┐
66       │Interface                │ Attribute     │ Value   │
67       ├─────────────────────────┼───────────────┼─────────┤
68       │erfc(), erfcf(), erfcl() │ Thread safety │ MT-Safe │
69       └─────────────────────────┴───────────────┴─────────┘

CONFORMING TO

71       C99, POSIX.1-2001, POSIX.1-2008.
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73       The variant returning double also conforms to SVr4, 4.3BSD.
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NOTES

76       The  erfc(),  erfcf(),  and erfcl() functions are provided to avoid the
77       loss accuracy that would occur for the calculation 1-erf(x)  for  large
78       values of x (for which the value of erf(x) approaches 1).
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SEE ALSO

81       cerf(3), erf(3), exp(3)
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COLOPHON

84       This  page  is  part of release 5.10 of the Linux man-pages project.  A
85       description of the project, information about reporting bugs,  and  the
86       latest     version     of     this    page,    can    be    found    at
87       https://www.kernel.org/doc/man-pages/.
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91GNU                               2017-09-15                           ERFC(3)
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