/**
* tests the firstDerivative function by comparison
*
* <p>This will test the functions <tt>f(x) = x^3 - 2x^2 + 6x + 3, g(x) = 3x^2 - 4x + 6</tt> and
* <tt>h(x) = 6x - 4</tt>
*/
public void testfirstDerivativeComparison() throws MathException {
double[] f_coeff = {3.0, 6.0, -2.0, 1.0};
double[] g_coeff = {6.0, -4.0, 3.0};
double[] h_coeff = {-4.0, 6.0};
PolynomialFunction f = new PolynomialFunction(f_coeff);
PolynomialFunction g = new PolynomialFunction(g_coeff);
PolynomialFunction h = new PolynomialFunction(h_coeff);
// compare f' = g
assertEquals(f.derivative().value(0.0), g.value(0.0), tolerance);
assertEquals(f.derivative().value(1.0), g.value(1.0), tolerance);
assertEquals(f.derivative().value(100.0), g.value(100.0), tolerance);
assertEquals(f.derivative().value(4.1), g.value(4.1), tolerance);
assertEquals(f.derivative().value(-3.25), g.value(-3.25), tolerance);
// compare g' = h
assertEquals(g.derivative().value(Math.PI), h.value(Math.PI), tolerance);
assertEquals(g.derivative().value(Math.E), h.value(Math.E), tolerance);
}
/**
* tests the value of a constant polynomial.
*
* <p>value of this is 2.5 everywhere.
*/
public void testConstants() throws MathException {
double[] c = {2.5};
PolynomialFunction f = new PolynomialFunction(c);
// verify that we are equal to c[0] at several (nonsymmetric) places
assertEquals(f.value(0.0), c[0], tolerance);
assertEquals(f.value(-1.0), c[0], tolerance);
assertEquals(f.value(-123.5), c[0], tolerance);
assertEquals(f.value(3.0), c[0], tolerance);
assertEquals(f.value(456.89), c[0], tolerance);
assertEquals(f.degree(), 0);
assertEquals(f.derivative().value(0), 0, tolerance);
assertEquals(f.polynomialDerivative().derivative().value(0), 0, tolerance);
}
