testPolynomialInterpolation.cc

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#include <cmath>
#include <iostream>
#include <vector>
#include <fstream>

#include <utl/Math.h>
#include <utl/PolynomialInterpolation.h>

#include <tst/Verify.h>
#include <cppunit/extensions/HelperMacros.h>

using namespace std;
using namespace utl;
using namespace tst;


class PolynomialInterpolationTest : public CppUnit::TestFixture {

  CPPUNIT_TEST_SUITE(PolynomialInterpolationTest);
  CPPUNIT_TEST(testSimple);
  CPPUNIT_TEST_SUITE_END();

public:
  void
  setUp()
  {
    fX.push_back(-1); fY.push_back(0);
    fX.push_back(0);  fY.push_back(1);
    fX.push_back(1);  fY.push_back(0);
    fX.push_back(2);  fY.push_back(2);
    fX.push_back(3);  fY.push_back(-1);
  }

  void tearDown() { }

  void
  testSimple()
  {
    const double np = 100;
    for (unsigned int n = 0; n <= fX.size(); ++n)
      for (int i = 0; i <= np; ++i) {
        const double x = -2 + i*6./np;
        double y = PolynomialInterpolation(n, &fX[0], &fY[0], x);
        const double expected = ExpectedValue(n, x);
        CPPUNIT_ASSERT(Verify<CloseTo>(y, expected));
        double dy;
        y = PolynomialInterpolation(n, &fX[0], &fY[0], x, dy);
        CPPUNIT_ASSERT(Verify<CloseTo>(y, expected));
      }
  }

private:
  vector<double> fX;
  vector<double> fY;

  double
  ExpectedValue(const unsigned int n, const double x)
  {
    switch (n) {
    case 0:
      return 0;
    case 1:
      return 0;
    case 2:
      return 1+x;
    case 3:
      return 1-Sqr(x);
    case 4:
      return 1-5*x/6-Sqr(x)+5*pow(x, 3)/6;
    case 5:
      return 1-23*x/12-11*Sqr(x)/24+23*pow(x, 3)/12-13*pow(x, 4)/24;
    }
    cerr << "ERROR!" << endl;
    return 0;
  }

};


CPPUNIT_TEST_SUITE_REGISTRATION(PolynomialInterpolationTest);


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