def Erfc(x):
    '''return the complementary of error function of x'''
    f = float(x)
    if (f == inf):
        return 0.0
    elif (f is -inf):
        return 2.0
##    elif (f == nan):
##        return nan
    else:
        if (abs(x)<0.84375):
            return erfc1(x)
        elif (0.84375<=abs(x)<1.25):
            return erfc2(x)
        elif (1.25<=abs(x)<2.857142):
            return erfc3(x)
        elif (2.857142<=abs(x)<6):
            return erfc4(x)
        elif (abs(x)>=6):
            return erfc5(x)
return the complementary of error function of x
recipes/Python/576391_error_functicomplementary_error/recipe-576391.py