public static LinearModel fit(Formula formula, DataFrame data) {
        return fit(formula, data, new Properties());
    }
@Test
    public void testCPU() {
        System.out.println("CPU");

        MathEx.setSeed(19650218); // to get repeatable results.

        LinearModel model = OLS.fit(CPU.formula, CPU.data);
        System.out.println(model);

        RegressionValidations<LinearModel> result = CrossValidation.regression(10, CPU.formula, CPU.data, OLS::fit);

        System.out.println(result);
        assertEquals(51.0009, result.avg.rmse, 1E-4);
    }