Ejemplo n.º 1
0
    public void testHalton()
    {
        //("Testing Halton sequences...");

            List<double> point;
            double tolerance = 1.0e-15;

            // testing "high" dimensionality
            int dimensionality = (int)SobolRsg.PPMT_MAX_DIM;
            HaltonRsg rsg = new HaltonRsg(dimensionality, 0, false, false);
            int points = 100, i, k;
            for (i = 0; i < points; i++)
            {
                point = rsg.nextSequence().value;
                if (point.Count != dimensionality)
                {
                    Assert.Fail("Halton sequence generator returns "+
                    " a sequence of wrong dimensionality: " + point.Count
                    + " instead of  " + dimensionality)
                    ;
                }
            }

            // testing first and second dimension (van der Corput sequence)
            double[] vanderCorputSequenceModuloTwo = {
                                                         // first cycle (zero excluded)
                                                         0.50000,
                                                         // second cycle
                                                         0.25000, 0.75000,
                                                         // third cycle
                                                         0.12500, 0.62500, 0.37500, 0.87500,
                                                         // fourth cycle
                                                         0.06250, 0.56250, 0.31250, 0.81250, 0.18750, 0.68750, 0.43750,
                                                         0.93750,
                                                         // fifth cycle
                                                         0.03125, 0.53125, 0.28125, 0.78125, 0.15625, 0.65625, 0.40625,
                                                         0.90625,
                                                         0.09375, 0.59375, 0.34375, 0.84375, 0.21875, 0.71875, 0.46875,
                                                         0.96875,
                                                     };

            dimensionality = 1;
            rsg = new HaltonRsg(dimensionality, 0, false, false);
            points = (int) (Math.Pow(2.0, 5)) - 1; // five cycles
            for (i = 0; i < points; i++)
            {
                point = rsg.nextSequence().value;
                double error = Math.Abs(point[0] - vanderCorputSequenceModuloTwo[i]);
                if (error > tolerance)
                {
                    Assert.Fail(i + 1 + " draw ("
                                + /*QL_FIXED*/ + point[0]
                                + ") in 1-D Halton sequence is not in the "
                                + "van der Corput sequence modulo two: "
                                + "it should have been "
                                + vanderCorputSequenceModuloTwo[i]
                                //+ QL_SCIENTIFIC
                                + " (error = " + error + ")");
                }
            }

            double[] vanderCorputSequenceModuloThree = {
                                                           // first cycle (zero excluded)
                                                           1.0/3, 2.0/3,
                                                           // second cycle
                                                           1.0/9, 4.0/9, 7.0/9, 2.0/9, 5.0/9, 8.0/9,
                                                           // third cycle
                                                           1.0/27, 10.0/27, 19.0/27, 4.0/27, 13.0/27, 22.0/27,
                                                           7.0/27, 16.0/27, 25.0/27, 2.0/27, 11.0/27, 20.0/27,
                                                           5.0/27, 14.0/27, 23.0/27, 8.0/27, 17.0/27, 26.0/27
                                                       };

            dimensionality = 2;
            rsg = new HaltonRsg(dimensionality, 0, false, false);
            points = (int) (Math.Pow(3.0, 3)) - 1; // three cycles of the higher dimension
            for (i = 0; i < points; i++)
            {
                point = rsg.nextSequence().value;
                double error = Math.Abs(point[0] - vanderCorputSequenceModuloTwo[i]);
                if (error > tolerance)
                {
                    Assert.Fail("First component of " + i + 1
                                + " draw (" + /*QL_FIXED*/ + point[0]
                                + ") in 2-D Halton sequence is not in the "
                                + "van der Corput sequence modulo two: "
                                + "it should have been "
                                + vanderCorputSequenceModuloTwo[i]
                                //+ QL_SCIENTIFIC
                                + " (error = " + error + ")");
                }
                error = Math.Abs(point[1] - vanderCorputSequenceModuloThree[i]);
                if (error > tolerance)
                {
                    Assert.Fail("Second component of " + i + 1
                                + " draw (" + /*QL_FIXED*/ + point[1]
                                + ") in 2-D Halton sequence is not in the "
                                + "van der Corput sequence modulo three: "
                                + "it should have been "
                                + vanderCorputSequenceModuloThree[i]
                                //+ QL_SCIENTIFIC
                                + " (error = " + error + ")");
                }
            }

            // testing homogeneity properties
            dimensionality = 33;
            rsg = new HaltonRsg(dimensionality, 0, false, false);
            SequenceStatistics stat = new SequenceStatistics(dimensionality);
            List<double> mean; //, stdev, variance, skewness, kurtosis;
            k = 0;
            int j;
            for (j = 1; j < 5; j++)
            {
                // five cycle
                points = (int) (Math.Pow(2.0, j)) - 1; // base 2
                for (; k < points; k++)
                {
                    point = rsg.nextSequence().value;
                    stat.add(point);
                }
                mean = stat.mean();
                double error = Math.Abs(mean[0] - 0.5);
                if (error > tolerance)
                {
                    Assert.Fail("First dimension mean (" + /*QL_FIXED*/ + mean[0]
                                + ") at the end of the " + j + 1
                                + " cycle in Halton sequence is not " + 0.5
                                //+ QL_SCIENTIFIC
                                + " (error = " + error + ")");
                }
            }

            // reset generator and gaussianstatistics
            rsg = new HaltonRsg(dimensionality, 0, false, false);
            stat.reset(dimensionality);
            k = 0;
            for (j = 1; j < 3; j++)
            {
                // three cycle
                points = (int) (Math.Pow(3.0, j)) - 1; // base 3
                for (; k < points; k++)
                {
                    point = rsg.nextSequence().value;
                    stat.add(point);
                }
                mean = stat.mean();
                double error = Math.Abs(mean[1] - 0.5);
                if (error > tolerance)
                {
                    Assert.Fail("Second dimension mean (" + /*QL_FIXED*/ + mean[1]
                                + ") at the end of the " + j + 1
                                + " cycle in Halton sequence is not " + 0.5
                                //+ QL_SCIENTIFIC
                                + " (error = " + error + ")");
                }
            }
    }
Ejemplo n.º 2
0
        public override void update()
        {
            this.coeff_.updateModelInstance();

            // we should also check that y contains positive values only

            // we must update weights if it is vegaWeighted
            if (vegaWeighted_)
            {
                coeff_.weights_.Clear();
                double weightsSum = 0.0;

                for (int i = 0; i < xBegin_.Count; i++)
                {
                    double stdDev = Math.Sqrt((yBegin_[i]) * (yBegin_[i]) * this.coeff_.t_);
                    coeff_.weights_.Add(coeff_.model_.weight(xBegin_[i], forward_, stdDev, this.coeff_.addParams_));
                    weightsSum += coeff_.weights_.Last();
                }

                // weight normalization
                for (int i = 0; i < coeff_.weights_.Count; i++)
                {
                    coeff_.weights_[i] /= weightsSum;
                }
            }

            // there is nothing to optimize
            if (coeff_.paramIsFixed_.Aggregate((a, b) => b && a))
            {
                coeff_.error_           = interpolationError();
                coeff_.maxError_        = interpolationMaxError();
                coeff_.XABREndCriteria_ = EndCriteria.Type.None;
                return;
            }
            else
            {
                XABRError costFunction = new XABRError(this);

                Vector guess = new Vector(coeff_.model_.dimension());
                for (int i = 0; i < guess.size(); ++i)
                {
                    guess[i] = coeff_.params_[i].Value;
                }

                int    iterations     = 0;
                int    freeParameters = 0;
                double bestError      = double.MaxValue;
                Vector bestParameters = new Vector();
                for (int i = 0; i < coeff_.model_.dimension(); ++i)
                {
                    if (!coeff_.paramIsFixed_[i])
                    {
                        ++freeParameters;
                    }
                }
                HaltonRsg        halton = new HaltonRsg(freeParameters, 42);
                EndCriteria.Type tmpEndCriteria;
                double           tmpInterpolationError;

                do
                {
                    if (iterations > 0)
                    {
                        Sample <List <double> > s = halton.nextSequence();
                        coeff_.model_.guess(guess, coeff_.paramIsFixed_, forward_, coeff_.t_, s.value, coeff_.addParams_);
                        for (int i = 0; i < coeff_.paramIsFixed_.Count; ++i)
                        {
                            if (coeff_.paramIsFixed_[i])
                            {
                                guess[i] = coeff_.params_[i].Value;
                            }
                        }
                    }

                    Vector inversedTransformatedGuess = new Vector(coeff_.model_.inverse(guess, coeff_.paramIsFixed_, coeff_.params_, forward_));

                    ProjectedCostFunction rainedXABRError = new ProjectedCostFunction(costFunction, inversedTransformatedGuess,
                                                                                      coeff_.paramIsFixed_);

                    Vector projectedGuess = new Vector(rainedXABRError.project(inversedTransformatedGuess));

                    NoConstraint raint   = new NoConstraint();
                    Problem      problem = new Problem(rainedXABRError, raint, projectedGuess);
                    tmpEndCriteria = optMethod_.minimize(problem, endCriteria_);
                    Vector projectedResult = new Vector(problem.currentValue());
                    Vector transfResult    = new Vector(rainedXABRError.include(projectedResult));
                    Vector result          = coeff_.model_.direct(transfResult, coeff_.paramIsFixed_, coeff_.params_, forward_);
                    tmpInterpolationError = useMaxError_ ? interpolationMaxError()
                                                     : interpolationError();

                    if (tmpInterpolationError < bestError)
                    {
                        bestError               = tmpInterpolationError;
                        bestParameters          = result;
                        coeff_.XABREndCriteria_ = tmpEndCriteria;
                    }
                } while (++iterations < maxGuesses_ &&
                         tmpInterpolationError > errorAccept_);

                for (int i = 0; i < bestParameters.size(); ++i)
                {
                    coeff_.params_[i] = bestParameters[i];
                }

                coeff_.error_    = interpolationError();
                coeff_.maxError_ = interpolationMaxError();
            }
        }