3.9.2.1.7 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]);
	}
}