PowerEval Routines

Summary

Evaluates power function.

Unit
RegModels

Declaration

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

Declaration

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

Result

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

Example 1

Evaluate power function for single x.

  Uses RegModels, Math387;
  procedure Example;
  var y: TSample;
  begin
    y := PowerEval([-5,3.5], 2.0);
    // y = -5.0*(2.0)^(3.5) = -56.568542495
  end;

  #include "Math387.hpp"
  #include "RegModels.hpp"
  void __fastcall Example();
  {
    double y = PowerEval(OPENARRAY(TSample,(-5,3.5)),2.0);
  }

  using Dew.Math;
  using Dew.Stats.Units;
  namespace Dew.Examples
  {
    private void Example()
    {
      y = RegModels.PowerEval(new double[] {-5,3.5},2.0);
    }
  }

Declaration

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

Description

Evaluates b[0]*X^b[1] 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 power function for multiple values at the same time. This is a lot faster than calling single value version for each x value.

See Also
PowerDeriv
PowerFit

Example 1

Evaluate power 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, 0.1); // x= -5.0, -4.9, ..., +4.9
    // Y = b[0] + b[1]*X
    PowerEval([1,3],X,Y);
    DrawValues(X,Y,Series1,false);
  end;

  #include "Math387.hpp"
  #include "RegModels.hpp"
  #include "MathExpr.hpp"
  #include "MtxVecTee.hpp"
  void __fastcall Example(TLineSeries* series);
  {
    Vector X,Y;
    X->Size(100,false);
    X->Ramp(-5.0, 0.1); // x= -5.0, -4.9, ..., +4.9
    PowerEval(OPENARRAY(TSample,(1.0, 3.0)),X,Y);
    DrawValues(X,Y,series,false);
  }

  using Dew.Math;
  using Dew.Stats.Units;
  namespace Dew.Examples
  {
    private void Example()
    {
      Vector X = new Vector(100,false);
      Vector Y = new Vector(0);
      X.Ramp(-5.0, 0.1);
      RegModels.PowerEval(new double[] {1.0, 3.0}, X, Y);
    }
  }