public void LogarithmRegressionRegressTest()
{
// This is the same data from the example available at
// http://mathbits.com/MathBits/TISection/Statistics2/logarithmic.htm
// Declare your inputs and output data
double[] inputs = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 };
double[] outputs = { 6, 9.5, 13, 15, 16.5, 17.5, 18.5, 19, 19.5, 19.7, 19.8 };
// Transform inputs to logarithms
double[] logx = Matrix.Log(inputs);
// Compute a simple linear regression
var lr = new SimpleLinearRegression();
// Compute with the log-transformed data
double error = lr.Regress(logx, outputs);
// Get an expression representing the learned regression model
// We just have to remember that 'x' will actually mean 'log(x)'
string result = lr.ToString("N4", CultureInfo.InvariantCulture);
// Result will be "y(x) = 6.1082x + 6.0993"
Assert.AreEqual(2.8760006026675797, error);
Assert.AreEqual(6.1081800414945704, lr.Slope);
Assert.AreEqual(6.0993411396126653, lr.Intercept);
Assert.AreEqual("y(x) = 6.1082x + 6.0993", result);
}
