@Test public void testTooLargeFirstStep() throws DimensionMismatchException, NumberIsTooSmallException, MaxCountExceededException, NoBracketingException { AdaptiveStepsizeIntegrator integ = new DormandPrince853Integrator(0, Double.POSITIVE_INFINITY, Double.NaN, Double.NaN); final double start = 0.0; final double end = 0.001; FirstOrderDifferentialEquations equations = new FirstOrderDifferentialEquations() { public int getDimension() { return 1; } public void computeDerivatives(double t, double[] y, double[] yDot) { Assert.assertTrue(t >= FastMath.nextAfter(start, Double.NEGATIVE_INFINITY)); Assert.assertTrue(t <= FastMath.nextAfter(end, Double.POSITIVE_INFINITY)); yDot[0] = -100.0 * y[0]; } }; integ.setStepSizeControl(0, 1.0, 1.0e-6, 1.0e-8); integ.integrate(equations, start, new double[] {1.0}, end, new double[1]); }
public void testDimensionCheck() { try { TestProblem1 pb = new TestProblem1(); AdaptiveStepsizeIntegrator integrator = new GraggBulirschStoerIntegrator(0.0, 1.0, 1.0e-10, 1.0e-10); integrator.integrate( pb, 0.0, new double[pb.getDimension() + 10], 1.0, new double[pb.getDimension() + 10]); fail("an exception should have been thrown"); } catch (DerivativeException de) { fail("wrong exception caught"); } catch (IntegratorException ie) { } }
@Test public void testIncreasingTolerance() throws DimensionMismatchException, NumberIsTooSmallException, MaxCountExceededException, NoBracketingException { int previousCalls = Integer.MAX_VALUE; AdaptiveStepsizeIntegrator integ = new DormandPrince853Integrator(0, Double.POSITIVE_INFINITY, Double.NaN, Double.NaN); for (int i = -12; i < -2; ++i) { TestProblem1 pb = new TestProblem1(); double minStep = 0; double maxStep = pb.getFinalTime() - pb.getInitialTime(); double scalAbsoluteTolerance = FastMath.pow(10.0, i); double scalRelativeTolerance = 0.01 * scalAbsoluteTolerance; integ.setStepSizeControl(minStep, maxStep, scalAbsoluteTolerance, scalRelativeTolerance); TestProblemHandler handler = new TestProblemHandler(pb, integ); integ.addStepHandler(handler); integ.integrate( pb, pb.getInitialTime(), pb.getInitialState(), pb.getFinalTime(), new double[pb.getDimension()]); // the 1.3 factor is only valid for this test // and has been obtained from trial and error // there is no general relation between local and global errors Assert.assertTrue(handler.getMaximalValueError() < (1.3 * scalAbsoluteTolerance)); Assert.assertEquals(0, handler.getMaximalTimeError(), 1.0e-12); int calls = pb.getCalls(); Assert.assertEquals(integ.getEvaluations(), calls); Assert.assertTrue(calls <= previousCalls); previousCalls = calls; } }