erf(3) - c6

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(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE;
20       or cc -std=c99
21       erff(), erfl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600||
22       _ISOC99_SOURCE; or cc -std=c99
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DESCRIPTION

25       The erf() function returns the error function of x, defined as
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27           erf(x) = 2/sqrt(pi)* integral from 0 to x of exp(-t*t) dt
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RETURN VALUE

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

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

54       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
55       4.3BSD.
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COLOPHON

61       This  page  is  part of release 3.22 of the Linux man-pages project.  A
62       description of the project, and information about reporting  bugs,  can
63       be found at http://www.kernel.org/doc/man-pages/.
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67GNU                               2008-08-05                            ERF(3)