RegModels.ExpFit Method

void ExpFit(TVec B, TVec X, TVec Y, TVec Weights)

Fits simple exponential equation to data.

#	Name	Description
1	X	Vector of independent variable.
2	Y	Vector of dependent variable.
3	Weights	Weights (optional). Weights are used only if they are set.
4	B	Returns regression coefficients for simple exponent function.

Result: stored in self (calling object)

Remarks:

The routine fits equations to data by minimizing the sum of squared residuals. The observed values obey the following equation:

Y=b[0]\cdot \exp \left(b[1]\cdot X\right) \quad .

Examples

using Dew.Math;
using Dew.Stats.Units;
namespace Dew.Examples
{
    private void Example(Steema.TeeChart.Styles.Line line1,
        Steema.TeeChart.Styles.Line line2)
    {
        Vector X = new Vector(100);
        Vector Y = new Vector(100);
        Vector B = new Vector(0);
        Vector YHat = new Vector(0);

        X.Ramp(-5.0, 0.05); // x= -5.0, -4.95, ... -0.05
        Y.RandGauss(3.5, 0.12); // sample data
        // calculate coefficients
        RegModels.ExpFit(B,X,Y,null);
        // evaluate y by using calculated coefficients
        RegModels.ExpEval(B,X, YHat);
        MtxVecTee.DrawValues(X,Y,line1,false);
        MtxVecTee.DrawValues(X,YHat,line2,false);
    }
}

See Also: RegModels.ExpDeriv, RegModels.ExpEval