Implicit Fit

Version Info

Minimum Origin Version Required: OriginPro 9.0 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 ellipse data.

1. Create a new worksheet and import the data <Origin Installation Directory>\Samples\Curve Fitting\Ellipse.dat.
2. Copy and compile the following codes in Code Builder, and then run "NLFitSession_Implicit_example1" in Command Window.

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

void NLFitSession_Implicit_example1(int nUseGetNBox = 0)
{
        // 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("Ellipse"))
        {
                out_str("Set fitting function error!");
                return;
        }
        
        // 2. set the data
        StringArray             vstrVars;
        int                                numVars;        
        if ( !FitSession.GetNumVars(NULL, &numVars, NULL, &vstrVars) )
        {
                out_str("Get variable error!");
                return;
        }     
        
        GETN_TREE(trInput);
        trInput.AddNode("InputData");
        int nDataRules = DRR_NO_FACTORS | DRR_NLFIT;
        trInput.InputData.SetAttribute(STR_DATA_RULES_ATTRIB, nDataRules);
        TreeNode trInputData;
        if ( !okutil_create_implicit_fitter_data_node_ex(&trInputData, &trInput, "InputData", "Input Data", &vstrVars, WEIGHT_NONE, TRUE) )
        {
                out_str("Create input data tree error!");
                return;
        }
        
        if ( nUseGetNBox )
        {
                trInput.FirstNode.SetAttribute(STR_ATTRIB_BRANCH, GETNBRANCH_OPEN);
                trInput.FirstNode.FirstNode.SetAttribute(STR_ATTRIB_BRANCH, GETNBRANCH_OPEN);
                if ( !GetNBox(trInput) )
                {
                        out_str("Set GetNBox InputData error!");
                        return;
                }
                trInputData = trInput.InputData;
        }
        else
        {
                TreeNode trRange = trInputData.FirstNode;
                TreeNode trX = trRange.FirstNode;
                TreeNode trWX = trX.NextNode;
                TreeNode trY = trWX.NextNode;
                TreeNode trWY = trY.NextNode;
                
                string          strRange;
                
                wks.Columns(0).GetRangeString(strRange);
                trX.strVal = strRange;
                wks.Columns(1).GetRangeString(strRange);
                trY.strVal = strRange;
                
                int                        nWeightMethod = WEIGHT_DIRECT;
                int                        nWA = 0, nWB = 0, nWC = 0;
                wks.Columns(2).GetRangeString(strRange);
                trWX.strVal = strRange;
                trWX.SetAttribute(STR_FITTER_WEIGHT_METHOD_ATTRIB, nWeightMethod);
                trWX.SetAttribute(STR_FITTER_WEIGHT_A_ATTRIB, nWA);
                trWX.SetAttribute(STR_FITTER_WEIGHT_B_ATTRIB, nWB);
                trWX.SetAttribute(STR_FITTER_WEIGHT_C_ATTRIB, nWC);
                wks.Columns(3).GetRangeString(strRange);
                trWY.strVal = strRange;
                trWY.SetAttribute(STR_FITTER_WEIGHT_METHOD_ATTRIB, nWeightMethod);
                trWY.SetAttribute(STR_FITTER_WEIGHT_A_ATTRIB, nWA);
                trWY.SetAttribute(STR_FITTER_WEIGHT_B_ATTRIB, nWB);
                trWY.SetAttribute(STR_FITTER_WEIGHT_C_ATTRIB, nWC);
        }
        
        if(!FitSession.SetData(trInputData))
        {
                out_str("Set data error!");
                return;
        }
        
        // 3. set parameter init values
        if(!FitSession.ParamsInitValues())
        {
                out_str("Init values error!");
                return;
        }
        
        // 4. start fitting 
        int nFitOutcome;
        if(!FitSession.Fit(&nFitOutcome))
        {
                string strOutcome = FitSession.GetFitOutCome(nFitOutcome);
                out_str("Fit error! "+strOutcome);
                return;
        }
        
        // 5. success, get results  
        RegStats fitStats;
        NLSFFitInfo fitInfo;
        FitSession.GetFitResultsStats(&fitStats, &fitInfo, false, 0);
        vector<string> vsParamNames;
        int nNumParamsInFunction = FitSession.GetParamNamesInFunction(vsParamNames);
        vector vParamValues, vErrors;
        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]);
        }
}