From 97bbb9cf251190fbf50a330360a7f353febbac3c Mon Sep 17 00:00:00 2001 From: Luc Maisonobe Date: Sat, 25 Apr 2009 16:59:19 +0000 Subject: [PATCH] fixed an Adams-Moulton order error, it was one unit too large and inconsistent with the order of the underlying predictor git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@768565 13f79535-47bb-0310-9956-ffa450edef68 --- .../ode/nonstiff/AdamsMoultonIntegrator.java | 10 ++++----- .../nonstiff/AdamsMoultonIntegratorTest.java | 22 +++++++++---------- 2 files changed, 16 insertions(+), 16 deletions(-) diff --git a/src/java/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegrator.java b/src/java/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegrator.java index fbeb7c7e2..f32acc8a9 100644 --- a/src/java/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegrator.java +++ b/src/java/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegrator.java @@ -83,7 +83,7 @@ public class AdamsMoultonIntegrator extends MultistepIntegrator { super(METHOD_NAME, order + 1, new AdamsMoultonStepInterpolator()); // compute the integration coefficients - int[][] bdArray = AdamsBashforthIntegrator.computeBackwardDifferencesArray(order + 1); + int[][] bdArray = AdamsBashforthIntegrator.computeBackwardDifferencesArray(order); Fraction[] gamma = AdamsBashforthIntegrator.computeGammaArray(order); predictorCoeffs = new double[order]; @@ -97,10 +97,10 @@ public class AdamsMoultonIntegrator extends MultistepIntegrator { } Fraction[] gammaStar = computeGammaStarArray(order); - correctorCoeffs = new double[order + 1]; - for (int i = 0; i <= order; ++i) { + correctorCoeffs = new double[order]; + for (int i = 0; i < order; ++i) { Fraction fCorrector = Fraction.ZERO; - for (int j = i; j <= order; ++j) { + for (int j = i; j < order; ++j) { Fraction f = new Fraction(bdArray[j][i], 1); fCorrector = fCorrector.add(gammaStar[j].multiply(f)); } @@ -272,7 +272,7 @@ public class AdamsMoultonIntegrator extends MultistepIntegrator { * @param order order of the integration method * @return gamma star coefficients array */ - static Fraction[] computeGammaStarArray(final int order) { + public static Fraction[] computeGammaStarArray(final int order) { // create the array Fraction[] gammaStarArray = new Fraction[order + 1]; diff --git a/src/test/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegratorTest.java b/src/test/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegratorTest.java index ae78da59f..b1330fe64 100644 --- a/src/test/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegratorTest.java +++ b/src/test/org/apache/commons/math/ode/nonstiff/AdamsMoultonIntegratorTest.java @@ -46,25 +46,25 @@ public class AdamsMoultonIntegratorTest public void testCorrectorCoefficients() { - double[] coeffs1 = new AdamsMoultonIntegrator(1, 0.01).getCorrectorCoeffs(); + double[] coeffs1 = new AdamsMoultonIntegrator(2, 0.01).getCorrectorCoeffs(); assertEquals(2, coeffs1.length); assertEquals(1.0 / 2.0, coeffs1[0], 1.0e-16); assertEquals(1.0 / 2.0, coeffs1[1], 1.0e-16); - double[] coeffs2 = new AdamsMoultonIntegrator(2, 0.01).getCorrectorCoeffs(); + double[] coeffs2 = new AdamsMoultonIntegrator(3, 0.01).getCorrectorCoeffs(); assertEquals(3, coeffs2.length); assertEquals( 5.0 / 12.0, coeffs2[0], 1.0e-16); assertEquals( 8.0 / 12.0, coeffs2[1], 1.0e-16); assertEquals(-1.0 / 12.0, coeffs2[2], 1.0e-16); - double[] coeffs3 = new AdamsMoultonIntegrator(3, 0.01).getCorrectorCoeffs(); + double[] coeffs3 = new AdamsMoultonIntegrator(4, 0.01).getCorrectorCoeffs(); assertEquals(4, coeffs3.length); assertEquals( 9.0 / 24.0, coeffs3[0], 1.0e-16); assertEquals(19.0 / 24.0, coeffs3[1], 1.0e-16); assertEquals(-5.0 / 24.0, coeffs3[2], 1.0e-16); assertEquals( 1.0 / 24.0, coeffs3[3], 1.0e-16); - double[] coeffs4 = new AdamsMoultonIntegrator(4, 0.01).getCorrectorCoeffs(); + double[] coeffs4 = new AdamsMoultonIntegrator(5, 0.01).getCorrectorCoeffs(); assertEquals(5, coeffs4.length); assertEquals( 251.0 / 720.0, coeffs4[0], 1.0e-16); assertEquals( 646.0 / 720.0, coeffs4[1], 1.0e-16); @@ -72,7 +72,7 @@ public class AdamsMoultonIntegratorTest assertEquals( 106.0 / 720.0, coeffs4[3], 1.0e-16); assertEquals( -19.0 / 720.0, coeffs4[4], 1.0e-16); - double[] coeffs5 = new AdamsMoultonIntegrator(5, 0.01).getCorrectorCoeffs(); + double[] coeffs5 = new AdamsMoultonIntegrator(6, 0.01).getCorrectorCoeffs(); assertEquals(6, coeffs5.length); assertEquals( 475.0 / 1440.0, coeffs5[0], 1.0e-16); assertEquals(1427.0 / 1440.0, coeffs5[1], 1.0e-16); @@ -81,7 +81,7 @@ public class AdamsMoultonIntegratorTest assertEquals(-173.0 / 1440.0, coeffs5[4], 1.0e-16); assertEquals( 27.0 / 1440.0, coeffs5[5], 1.0e-16); - double[] coeffs6 = new AdamsMoultonIntegrator(6, 0.01).getCorrectorCoeffs(); + double[] coeffs6 = new AdamsMoultonIntegrator(7, 0.01).getCorrectorCoeffs(); assertEquals(7, coeffs6.length); assertEquals( 19087.0 / 60480.0, coeffs6[0], 1.0e-16); assertEquals( 65112.0 / 60480.0, coeffs6[1], 1.0e-16); @@ -91,7 +91,7 @@ public class AdamsMoultonIntegratorTest assertEquals( 6312.0 / 60480.0, coeffs6[5], 1.0e-16); assertEquals( -863.0 / 60480.0, coeffs6[6], 1.0e-16); - double[] coeffs7 = new AdamsMoultonIntegrator(7, 0.01).getCorrectorCoeffs(); + double[] coeffs7 = new AdamsMoultonIntegrator(8, 0.01).getCorrectorCoeffs(); assertEquals(8, coeffs7.length); assertEquals( 36799.0 / 120960.0, coeffs7[0], 1.0e-16); assertEquals( 139849.0 / 120960.0, coeffs7[1], 1.0e-16); @@ -102,7 +102,7 @@ public class AdamsMoultonIntegratorTest assertEquals( -11351.0 / 120960.0, coeffs7[6], 1.0e-16); assertEquals( 1375.0 / 120960.0, coeffs7[7], 1.0e-16); - double[] coeffs8 = new AdamsMoultonIntegrator(8, 0.01).getCorrectorCoeffs(); + double[] coeffs8 = new AdamsMoultonIntegrator(9, 0.01).getCorrectorCoeffs(); assertEquals(9, coeffs8.length); assertEquals( 1070017.0 / 3628800.0, coeffs8[0], 1.0e-16); assertEquals( 4467094.0 / 3628800.0, coeffs8[1], 1.0e-16); @@ -183,9 +183,9 @@ public class AdamsMoultonIntegratorTest pb.getInitialTime(), pb.getInitialState(), pb.getFinalTime(), new double[pb.getDimension()]); - assertTrue(handler.getLastError() < 7.0e-12); - assertTrue(handler.getMaximalValueError() < 4.0e-11); - assertEquals(0, handler.getMaximalTimeError(), 1.0e-14); + assertTrue(handler.getLastError() < 3.0e-10); + assertTrue(handler.getMaximalValueError() < 2.0e-9); + assertEquals(0, handler.getMaximalTimeError(), 1.0e-15); assertEquals("Adams-Moulton", integ.getName()); }