Fitting subrange data with constraints

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I am trying to fit data for subrange of Xvalues (independent variable) with fit coefficients in between 0 and 1. Right now, I am extracting subrange of data but this is time and space consuming. As an alternative I tried with this code but fit for subrange of data is not working. Here is the snippet of the code

Function FitSpectrum(ww,xx) : FitFunc

	WAVE ww 
 	variable xx	
	SetScale/I X, 5,30
	Variable w1=0,w2=0,w3=0,w4=0,w5=0,w6=0,w7=0,qq=0
	Variable T1=0.24, S1=0.047, T2=0.24, S2=0.047, x1=1.908, x2=1.918,
	//Variable StartP, EndP
	//StartP=xx[5]
	//EndP=xx[30]
	w1 = exp(0.5*(S1/T1)^2-(xx-x1)/T1)   
	w2 = erfc(0.707*(S1/T1-(xx-x1)/S1))
	w3 = ww[0]
        w7 = ww[1]
        w8 = exp(-((xx-x3)/S3)^2
        qq = w3*(w1*w2)+w7*w8
return qq

////////////
I called this fit equation to fit mulitple spectrums that make up a 2D data (raw data) using this code


Function ProcessData(DataFolderName, DataName)
String DataFolderName, DataName   
Variable i
	DFRef OldDF=GetDataFolderDFR()
	SetDataFolder $DataFolderName
	Wave Data=$DataName
	Duplicate /O Data $("fit_"+DataName) 
	Make /O /N=(DimSize(Data,1)) A1, A2
	Make/O/D/N=2 T_Constraints
	Make /FREE /D /N=2 w_coef={1,2}
	Make /FREE /N=(Dimsize(Data,0)) Fit
	SetScale X, 5,30
	For (i=0;i 1e-10,A1[i] < 1.0001,A2[i] > 1e-10,A2[i] < 1.0001}
	     FuncFit /Q FitSpectrum w_coef Data[][i]/D=Fit/C=T_Constraints                           //this fit function for constraint works
             //FuncFit /Q FitSpectrum w_coef Data[][i]/D=Fit/X=xx(5, 30)/C=T_Constraints         // does not work when flag for subrange of data is added  


I would appreciate any thoughts or help.
You need to specify a wavename for SetScale. I would also only run SetScale once outside the FitFunc instead of inside the FitFunc.

The constraint wave also need to be a text wave and you have to use K0, K1, K2 etc... to describe your variables (In your case K0 is w_coef[0] and K1 is w_coef[1]). A statement such as "A1[i] > 1e-10" makes no sense since A1 is not a fit variable. Read 
DisplayHelpTopic "Fitting with Constraints"

January 22, 2018 at 02:04 am - Permalink
Thanks Olelytken for your feedback. I think I undesrtood now why fitting constraints work even if I disable the code. It worked because at first I created a textwave for the fitting constraints, K's which was stored in the data folder and later to fix issues of subrange data I might have replaced them with A's in the procedure file.
Coming back to the subrange data, the fit does not work and I am assuming error in the line where I call Funcfit

Function ProcessData(DataFolderName, DataName)
String DataFolderName, DataName   
Variable i
	DFRef OldDF=GetDataFolderDFR()
	SetDataFolder $DataFolderName
	Wave Data=$DataName
SetScale/I X, 5,30, Data          
.......
 FuncFit /Q FitSpectrum w_coef Data[][i]/D=Fit/X=Data(5, 30)/C=T_Constraints

January 22, 2018 at 09:50 am - Permalink