/**
* Test with perfect data
*/
//@Test
public void testPerfect()
{
double[] coef = new double[] { 1, -2, 3 };
double[] x = new double[] { -2, 1, 0.5, 2, 3, 4, 5, 7, 8, 9.2, 10.2, 4.3, 6.7 };
double[] y = new double[x.Length];
for (int i = 0; i < y.Length; i++)
{
double v = 0;
double xx = 1;
foreach (double c in coef)
{
v += c * xx;
xx *= x[i];
}
y[i] = v;
}
PolynomialFit alg = new PolynomialFit(2);
alg.fit(x, y);
double[] found = alg.getCoef();
for (int i = 0; i < coef.Length; i++)
{
Assert.IsTrue(Math.Abs(coef[i] - found[i]) < UtilEjml.TEST_F64);
}
}
/**
* Make one of the observations way off and see if it is removed
*/
//@Test
public void testNoise()
{
double[] coef = new double[] { 1, -2, 3 };
double[] x = new double[] { -2, 1, 0.5, 2, 3, 4, 5, 7, 8, 9.2, 10.2, 4.3, 6.7 };
double[] y = new double[x.Length];
for (int i = 0; i < y.Length; i++)
{
double v = 0;
double xx = 1;
foreach (double c in coef)
{
v += c * xx;
xx *= x[i];
}
y[i] = v;
}
y[4] += 3.5;
PolynomialFit alg = new PolynomialFit(2);
alg.fit(x, y);
double[] found = alg.getCoef();
// the coefficients that it initialy computes should be incorrect
for (int i = 0; i < coef.Length; i++)
{
Assert.IsTrue(Math.Abs(coef[i] - found[i]) > UtilEjml.TEST_F64);
}
//remove the outlier
alg.removeWorstFit();
// now see if the solution is perfect
found = alg.getCoef();
for (int i = 0; i < coef.Length; i++)
{
Assert.IsTrue(Math.Abs(coef[i] - found[i]) < UtilEjml.TEST_F64);
}
}