def conf_int(x, p=0.05):
    """Confidence interval of a normally distributed array."""
    x = sorted(x)
    l = len(x)
    i1 = int(round(p / 2 * l + 0.5))
    i2 = int(round((1 - p / 2) * l - 0.5))
    ci1 = x[i1]
    ci2 = x[i2]
    return ci1, ci2
