ExpEval Routines

Summary

Evaluates exponential function.

Declaration

Procedure ExpEval(const B: array of TSample; X, YHat: TVec);

Description

Evaluates b[0]*Exp(b[1]*X) for given values in X vector, parameters in B array, and returns the results in XHat vector. Size and Complex properties of XHat vector are adjusted automatically.

Use this version if you want to evaluate exponential function for multiple values at the same time. This is a lot faster than calling single value version for each x value.

See Also
ExpDeriv
ExpFit

Example 1

Evaluate exponential function for multiple values at the same time.

  Uses MathExpr, MtxVecTee, Series, RegModels;
  procedure Example(Series1: TLineSeries);
  var Y,X: Vector;
  begin
    X.Size(100);
    X.Ramp(-5.0, 0.05); // x= -5.0, -4.95, ... -0.05
    // Y = b[0] + b[1]*X
    ExpEval([1,3],X,Y);
    DrawValues(X,Y,Series1,false);
  end;

  #include "Math387.hpp"
  #include "RegModels.hpp"
  void __fastcall Example(TLineSeries* Series1);
  {
    Vector X,Y;
    X->Size(100,false);
    X->Ramp(-5.0, 0.05); // x= -5.0, -4.95, ... -0.05
    ExpEval(OPENARRAY(TSample,(3.0, -0.5)),X,Y);
    DrawValues(X,Y,Series1,false);
  }

  using Dew.Math;
  using Dew.Stats.Units;
  namespace Dew.Examples
  {
    private void Example(Steema.TeeChart.Styles.Line line1)
    {
      Vector X = new Vector(100);
      Vector Y = new Vector(0);
      X.Ramp(-5.0, 0.05); // x= -5.0, -4.95, ... -0.05
      // Y = b[0] + b[1]*X
      RegModels.ExpEval(new double[] {1,3},X,Y);
      MtxVecTee.DrawValues(X,Y,line1,false);
    }
  }

Declaration

Function ExpEval(const B: array of TSample; X: TSample): TSample;

Result

b[0]*Exp(b[1]*X) for given value X and parameters in B array.

Example 1

Evaluate exponential function for single x.

  Uses Math387, RegModels;
  var y: TSample;
  begin
    y := ExpEval([3,-0.5], 1.5);
    // Res = 3*Exp(-0.5*1.5) = 1.4170996582
  end;

  #include "Math387.hpp"
  #include "RegModels.hpp"
  void __fastcall Example();
  {
    double y = ExpEval(OPENARRAY(TSample,(3.0, -0.5)),1.5);
    // y = 3*Exp(-0.5*1.5) = 1.4170996582
  }

  using Dew.Math;
  using Dew.Stats.Units;
  namespace Dew.Examples
  {
    private void Example()
    {
      double y = RegModels.ExpEval(new double[] {3.0, -0.5}, 1.5);
      // y = 3*Exp(-0.5*1.5) = 1.4170996582
    }
  }

Declaration

Procedure ExpEval(B, X, YHat: TVec);

Description

The B parameter can be a vector.