erfcl(3) - f37

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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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24       erfcf(), erfcl():
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 complementary error function of x, that is,
31       1.0 - erf(x).
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RETURN VALUE

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

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

63       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
64       tributes(7).
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66       ┌────────────────────────────────────────────┬───────────────┬─────────┐
67       │Interface                                   │ Attribute     │ Value   │
68       ├────────────────────────────────────────────┼───────────────┼─────────┤
69       │erfc(), erfcf(), erfcl()                    │ Thread safety │ MT-Safe │
70       └────────────────────────────────────────────┴───────────────┴─────────┘
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CONFORMING TO

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

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

86       This  page  is  part of release 5.13 of the Linux man-pages project.  A
87       description of the project, information about reporting bugs,  and  the
88       latest     version     of     this    page,    can    be    found    at
89       https://www.kernel.org/doc/man-pages/.
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93GNU                               2021-03-22                           ERFC(3)