test_utils.cpp

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#include <gtest/gtest.h>
#include <spline_smoother/spline_smoother_utils.h>
#include <stdlib.h>

static double getRandomNumber(double min, double max)
{
  return ((double)rand() / RAND_MAX)*(max-min) + min;
}

TEST(TestUtils, testTridiagonalSolver)
{
  // seed the random number generator:
  srand(2);

  // generate a random tridiagonal matrix:
  int n=10;

  std::vector<double> a(n);
  std::vector<double> b(n);
  std::vector<double> c(n);
  std::vector<double> d(n);
  std::vector<double> x(n);
  std::vector<double> solved_x(n);

  for (int i=0; i<n; i++)
  {
    a[i] = getRandomNumber(10.0, 20.0);
    b[i] = getRandomNumber(1.0, 4.0);
    c[i] = getRandomNumber(1.0, 4.0);
    x[i] = getRandomNumber(-1.0, 1.0);
  }
  a[0] = 0.0;
  c[n-1] = 0.0;

  // multiply to get values for d:
  for (int i=1; i<n-1; i++)
  {
    d[i] = a[i]*x[i-1] + b[i]*x[i] + c[i]*x[i+1];
  }
  d[0] = b[0]*x[0] + c[0]*x[1];
  d[n-1] = a[n-1]*x[n-2] + b[n-1]*x[n-1];

  // solve it:
  spline_smoother::tridiagonalSolve(a, b, c, d, solved_x);

  double tolerance = 1e-8;

  // check it:
  for (int i=0; i<n; i++)
  {
    EXPECT_NEAR(x[i], solved_x[i], tolerance);
  }
}

TEST(TestUtils, testTridiagonalSolver2)
{
  // seed the random number generator:
  srand(2);

  // generate a tridiagonal matrix for cubic splines
  int n=10;

  std::vector<double> a(n);
  std::vector<double> b(n);
  std::vector<double> c(n);
  std::vector<double> d(n);
  std::vector<double> x(n);
  std::vector<double> solved_x(n);

  for (int i=0; i<n; i++)
  {
    a[i] = 4.0;
    b[i] = 1.0;
    c[i] = 1.0;
    x[i] = getRandomNumber(-1.0, 1.0);
  }
  a[0] = 0.0;
  c[n-1] = 0.0;
  b[0] = 2.0;
  b[n-1] = 2.0;

  // multiply to get values for d:
  for (int i=1; i<n-1; i++)
  {
    d[i] = a[i]*x[i-1] + b[i]*x[i] + c[i]*x[i+1];
  }
  d[0] = b[0]*x[0] + c[0]*x[1];
  d[n-1] = a[n-1]*x[n-2] + b[n-1]*x[n-1];

  // solve it:
  spline_smoother::tridiagonalSolve(a, b, c, d, solved_x);

  double tolerance = 1e-8;

  // check it:
  for (int i=0; i<n; i++)
  {
    EXPECT_NEAR(x[i], solved_x[i], tolerance);
  }
}

---

spline_smoother
Author(s): Mrinal Kalakrishnan / mail@mrinal.net
autogenerated on Fri Jan 11 09:15:07 2013