Weighted Fitting

Version Info

Minimum Origin Version Required: Origin 8.1 SR0

Need to do before Running Examples

Prior to running the following example, the nlsf_utils.c file need to be loaded and compiled. This can be done from script with the following command or just add this file to your workspace.

run.LoadOC(Originlab\nlsf_utils.c);

Example

The following code shows how to use NLFitSesssion to fit with weighted data.

1. Create a new worksheet and import the data <Origin Installation Directory>\Samples\Curve Fitting\Gaussian.dat.
2. Copy and compile the following codes in Code Builder, and then run "Weighted_Fitting" in Command Window.

#include <..\originlab\NLFitSession.h>

void Weighted_Fitting()
{
        // get the active worksheet
        Worksheet wks = Project.ActiveLayer();
        if(!wks)
        {
                out_str("Not a valid worksheet!");
                return; // need to activate a worksheet with data
        }
        
        NLFitSession FitSession;
        
        // 1. set function
        if(!FitSession.SetFunction("Gauss"))
        {
                out_str("Set fitting function error!");
                return;
        }
        
        // get parameter names and number
        vector<string> vsParamNames;
        int nNumParamsInFunction = FitSession.GetParamNamesInFunction(vsParamNames);
        
        // get data range
        DataRange drInputData;
        drInputData.Add(wks, 0, "X");  // x column
        drInputData.Add(wks, 1, "Y");  // y column
        drInputData.Add(wks, 2, "ED");  // weight column
        
        // 2. set the dataset
        vector vX, vY, vW;
        drInputData.GetData(&vX, 0);
        drInputData.GetData(&vY, 1);
        drInputData.GetData(&vW, 2);
        
        if(!FitSession.SetData(vY, vX, NULL, 0, 1, DATA_MODE_INDEP_CONSOLID, vW))
        {
                out_str("Set data error!");
                return;
        }
        
        // 3. set parameter init values
        if(!FitSession.ParamsInitValues())
        {
                out_str("Init values error!");
                return;
        }
        
        // 4. set weight method, WEIGHT_NONE = no weight, WEIGHT_INSTRUMENTAL = instrumental
        // WEIGHT_STATISTICAL = statistics
        if(!FitSession.SetWeightData(WEIGHT_INSTRUMENTAL, 0.0, 0.0, 0.0))
        {
                out_str("Set weight method error!");
                return;
        }
                        
        // 5. start fitting       
        int nFitOutcome;
        if(!FitSession.Fit(&nFitOutcome))
        {
                string strOutcome = FitSession.GetFitOutCome(nFitOutcome);
                out_str("Fit error! "+strOutcome);
                return;
        }
        
        // 6. success, get results        
        RegStats fitStats;
        NLSFFitInfo fitInfo;
        vector vParamValues, vErrors;
        FitSession.GetFitResultsStats(&fitStats, &fitInfo, false, 0);
        FitSession.GetFitResultsParams(vParamValues, vErrors);
        
        printf("# Iterations = %d, Reduced Chisqr = %g\n", fitInfo.Iterations, fitStats.ReducedChiSq);
        for(int nParam=0; nParam<vParamValues.GetSize(); nParam++)
        {
                printf("# %s = %f, %s_error = %f\n", vsParamNames[nParam], vParamValues[nParam], vsParamNames[nParam], vErrors[nParam]);
        }
}