### Question:
PolynomialFunction2D implements Function2D, Serializable { public int getOrder() { return this.coefficients.length - 1; } PolynomialFunction2D(double[] coefficients); double[] getCoefficients(); int getOrder(); @Override double getValue(double x); @Override boolean equals(Object obj); @Override int hashCode();  }### Answer:
@Test public void testGetOrder() { PolynomialFunction2D f = new PolynomialFunction2D(new double[] {1.0, 2.0}); assertEquals(1, f.getOrder()); }