@Test(expectedExceptions = IllegalArgumentException.class) public void testNullWeights() { new GaussianQuadratureData(X, null); }
@Test(expectedExceptions = IllegalArgumentException.class) public void testWrongLength() { new GaussianQuadratureData(X, new double[] {1, 2, 3 }); }
@Test(expectedExceptions = IllegalArgumentException.class) public void testNullAbscissas() { new GaussianQuadratureData(null, W); }
@Test public void test() { GaussianQuadratureData other = new GaussianQuadratureData(X, W); assertEquals(F, other); assertEquals(F.hashCode(), other.hashCode()); other = new GaussianQuadratureData(W, W); assertFalse(F.equals(other)); other = new GaussianQuadratureData(X, X); assertFalse(F.equals(other)); assertArrayEquals(F.getAbscissas(), X, 0); assertArrayEquals(F.getWeights(), W, 0); } }
/** * {@inheritDoc} */ @Override public GaussianQuadratureData generate(int n) { ArgChecker.isTrue(n > 0); int mid = (n + 1) / 2; double[] x = new double[n]; double[] w = new double[n]; Pair<DoubleFunction1D, DoubleFunction1D>[] polynomials = LEGENDRE.getPolynomialsAndFirstDerivative(n); Pair<DoubleFunction1D, DoubleFunction1D> pair = polynomials[n]; DoubleFunction1D function = pair.getFirst(); DoubleFunction1D derivative = pair.getSecond(); for (int i = 0; i < mid; i++) { double root = ROOT_FINDER.getRoot(function, derivative, getInitialRootGuess(i, n)); x[i] = -root; x[n - i - 1] = root; double dp = derivative.applyAsDouble(root); w[i] = 2 / ((1 - root * root) * dp * dp); w[n - i - 1] = w[i]; } return new GaussianQuadratureData(x, w); }
@Override public GaussianQuadratureData generate(int n) { ArgChecker.isTrue(n > 0); double[] x = new double[n]; double[] w = new double[n]; boolean odd = n % 2 != 0; int m = (n + 1) / 2 - (odd ? 1 : 0); Pair<DoubleFunction1D, DoubleFunction1D>[] polynomials = HERMITE.getPolynomialsAndFirstDerivative(n); Pair<DoubleFunction1D, DoubleFunction1D> pair = polynomials[n]; DoubleFunction1D function = pair.getFirst(); DoubleFunction1D derivative = pair.getSecond(); double root = 0; for (int i = 0; i < m; i++) { root = getInitialRootGuess(root, i, n, x); root = ROOT_FINDER.getRoot(function, derivative, root); double dp = derivative.applyAsDouble(root); x[i] = -root; x[n - 1 - i] = root; w[i] = 2. / (dp * dp); w[n - 1 - i] = w[i]; } if (odd) { double dp = derivative.applyAsDouble(0.0); w[m] = 2. / dp / dp; } return new GaussianQuadratureData(x, w); }
/** * {@inheritDoc} */ @Override public GaussianQuadratureData generate(int n) { ArgChecker.isTrue(n > 0, "n > 0"); Pair<DoubleFunction1D, DoubleFunction1D>[] polynomials = JACOBI.getPolynomialsAndFirstDerivative(n, _alpha, _beta); Pair<DoubleFunction1D, DoubleFunction1D> pair = polynomials[n]; DoubleFunction1D previous = polynomials[n - 1].getFirst(); DoubleFunction1D function = pair.getFirst(); DoubleFunction1D derivative = pair.getSecond(); double[] x = new double[n]; double[] w = new double[n]; double root = 0; for (int i = 0; i < n; i++) { double d = 2 * n + _c; root = getInitialRootGuess(root, i, n, x); root = ROOT_FINDER.getRoot(function, derivative, root); x[i] = root; w[i] = GAMMA_FUNCTION.applyAsDouble(_alpha + n) * GAMMA_FUNCTION.applyAsDouble(_beta + n) / CombinatoricsUtils.factorialDouble(n) / GAMMA_FUNCTION.applyAsDouble(n + _c + 1) * d * Math.pow(2, _c) / (derivative.applyAsDouble(root) * previous.applyAsDouble(root)); } return new GaussianQuadratureData(x, w); }
/** * {@inheritDoc} */ @Override public GaussianQuadratureData generate(int n) { ArgChecker.isTrue(n > 0); Pair<DoubleFunction1D, DoubleFunction1D>[] polynomials = LAGUERRE.getPolynomialsAndFirstDerivative(n, _alpha); Pair<DoubleFunction1D, DoubleFunction1D> pair = polynomials[n]; DoubleFunction1D p1 = polynomials[n - 1].getFirst(); DoubleFunction1D function = pair.getFirst(); DoubleFunction1D derivative = pair.getSecond(); double[] x = new double[n]; double[] w = new double[n]; double root = 0; for (int i = 0; i < n; i++) { root = ROOT_FINDER.getRoot(function, derivative, getInitialRootGuess(root, i, n, x)); x[i] = root; w[i] = -GAMMA_FUNCTION.applyAsDouble(_alpha + n) / CombinatoricsUtils.factorialDouble(n) / (derivative.applyAsDouble(root) * p1.applyAsDouble(root)); } return new GaussianQuadratureData(x, w); }