### Question:
PolyUtils { public static int degreeFromCoefficients(int numOfCoefficients) { return (int) (0.5 * (-1 + (int) (Math.sqrt((double) (1 + 8 * numOfCoefficients))))) - 1; }  static double normalize2(double data, final int min, final int max); static double normalize2(double data, final double min, final double max); static DoubleMatrix normalize(DoubleMatrix t); static int degreeFromCoefficients(int numOfCoefficients); static int numberOfCoefficients(final int degree); static double[] polyFitNormalized(DoubleMatrix t, DoubleMatrix y, final int degree); static double[] polyFit2D(final DoubleMatrix x, final DoubleMatrix y, final DoubleMatrix z, final int degree); static double[] polyFit(DoubleMatrix t, DoubleMatrix y, final int degree); static double polyVal1D(double x, double[] coeffs); static double[][] polyval(final double[] x, final double[] y, final double coeff[], int degree); static DoubleMatrix polyval(final DoubleMatrix x, final DoubleMatrix y, final DoubleMatrix coeff, int degree); static double polyval(final double x, final double y, final DoubleMatrix coeff, int degree); static double polyval(final double x, final double y, final double[] coeff); static double polyval(final double x, final double y, final double[] coeff, int degree);  }### Answer:
@Test public void testDegreeFromCoefficients() throws Exception { final int degree_EXPECTED = 5; int degree_ACTUAL = PolyUtils.degreeFromCoefficients(21); Assert.assertEquals(degree_EXPECTED, degree_ACTUAL); }