void _nlsfPDEM(
// Fit Parameter(s):
double a, double m,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y)
{
	// Beginning of editable part
		NLFitContext *pCtxt = Project.GetNLFitContext();
	        Worksheet wks;
	        DataRange dr;
	        int c1,c2;
	        dr = pCtxt->GetSourceDataRange(); //Get the source data range
	        dr.GetRange(wks, c1, c2);  //Get the source data worksheet
	        if ( pCtxt )
		{	
			// Vector for the output signal in each iteration.
			static vector vdeformation;
			// If parameters were updated, we will recalculate the convolution result.
			BOOL bIsNewParamValues = pCtxt->IsNewParamValues();
			if ( bIsNewParamValues )
			{
				// Read sampling and response data from worksheet.
				Dataset dscycles(wks, 0);
				Dataset dsdeformation(wks, 1);
				int iSize = dscycles.GetSize();
	 
				vector vcycles, vdeformation, vC;
	 
				vcycles = dscycles;
				vdeformation = dsdeformation;
	 
				vcycles.SetSize(iSize);
				vdeformation.SetSize(iSize);
				vC.SetSize(iSize);
				// Compute the PDEM
				vC=a+(m*vcycles)
				vdeformation[iSize] = (2*(vdeformation[iSize-1])^(1-vC))-(vdeformation[iSize-2])^(1-vC))^(1/(1-vC));
				// Perform convolution
				int iRet = fft_fft_convolution(iSize, vdeformation, vcycles);
	           //Correct the convolution by multiplying the sampling interval
	            vdeformation = (vcycles[1]-vcycles[0])*vdeformation;
	 
	 		}
	 		NLSFCURRINFO    stCurrInfo;
		pCtxt->GetFitCurrInfo(&stCurrInfo);
		// Get the data index for the iteration
		int nCurrentIndex = stCurrInfo.nCurrDataIndex;
		// Get the evaluated y value
		y = vdeformation[nCurrentIndex];
		// For compile the function, since we haven't use x here.
		x;
	}
	// End of editable part

quote:

---

Originally posted by yuki_wu

Hi Nithin S,

Firstly, you need to define the two initial values of y_data, y0 and y1, as parameters.

In order to get the fitted y_data during fitting, you need to use several methods of NLFitContext class, including GetSourceDataRange, IsNewParamValues, GetFitCurrInfo:
http://www.originlab.com/doc/OriginC/ref/NLFitContext

Basically, you can refer to this tutorial, it may help you to create your own fitting function by imitating the code of that example.
http://www.originlab.com/doc/Tutorials/Fitting-Convolution

Hope it helps.

Regards,
Yuki
OriginLab

---

void _nlsfPDEM(
// Fit Parameter(s):
double a, double m, double y0, double y1,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y)
{
	…
	vector  vydata;
	vydata[0] = y0;
	vydata[1] = y1;
	…
}

void _nlsfPDEM(
// Fit Parameter(s):
double a, double m,
// Independent Variable(s):
double x,
// Dependent Variable(s):
double& y)
{
	…
	vector  vydata;	
	vydata[0] = 1;
	vydata[1] = 2;
	…
}