public static String diff(double[] o, double[] p) {
        String status = "ok.";
        if (o.length != p.length) {
            status = "o.length != p.length";
        } else {
            for (int i = 0; i < o.length; i++) {
                if (o[i] != p[i]) {
                    status += "error";
                }
            }
        }
        return status;
    }