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

NAME
       erfc, erfcf, erfcl - complementary error function

SYNOPSIS
       #include 

       double erfc(double x);
       float erfcf(float x);
       long double erfcl(long double x);

       Link with -lm.

   Feature Test Macro Requirements for glibc (see featuretestmacros(7)):

       erfc():
           BSDSOURCE || SVIDSOURCE || XOPENSOURCE || ISOC99SOURCE ||
           POSIXCSOURCE >= 200112L;
           or cc -std=c99
       erfcf(), erfcl():
           BSDSOURCE || SVIDSOURCE || XOPENSOURCE >= 600||
           ISOC99SOURCE || POSIXCSOURCE >= 200112L;
           or cc -std=c99

DESCRIPTION
       The erfc() function returns the complementary error function of x, that
       is, 1.0 - erf(x).

RETURN VALUE
       On success, these functions return the complementary error function  of
       x, a value in the range [0,2].

       If x is a NaN, a NaN is returned.

       If x is +0 or -0, 1 is returned.

       If x is positive infinity, +0 is returned.

       If x is negative infinity, +2 is returned.

       If  the  function  result  underflows  and  produces an unrepresentable
       value, the return value is 0.0.

       If the function result underflows but produces a  representable  (i.e.,
       subnormal) value, that value is returned, and a range error occurs.

ERRORS
       See  matherror(7) for information on how to determine whether an error
       has occurred when calling these functions.

       The following errors can occur:

       Range error: result underflow (result is subnormal)
              An underflow floating-point exception (FEUNDERFLOW) is raised.

       These functions do not set errno.

ATTRIBUTES
       For  an  explanation  of  the  terms  used   in   this   section,   see
       attributes(7).

       ┌─────────────────────────┬───────────────┬─────────┐
       │Interface                │ Attribute     │ Value   │
       ├─────────────────────────┼───────────────┼─────────┤
       │erfc(), erfcf(), erfcl() │ Thread safety │ MT-Safe │
       └─────────────────────────┴───────────────┴─────────┘
CONFORMING TO
       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
       4.3BSD.

NOTES
       The erfc() functions are provided to avoid the loss accuracy that would
       occur for the calculation 1-erf(x) for large values of x (for which the
       value of erf(x) approaches 1).

SEE ALSO
       cerf(3), erf(3), exp(3)

COLOPHON
       This page is part of release 3.53 of the Linux  man-pages  project.   A
       description  of  the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



GNU                               2010-09-20                           ERFC(3)