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T O P I C    R E V I E W
junsung Posted - 11/14/2006 : 12:01:54 PM
Origin Version (Select Help-->About Origin): 7.5853
Operating System: Window XP (SP2)

Hi, all
I tried to do some fitting using interpolation, but it seems not working well. My fitting function cannot be written in an equation form, so I have only a data set, F[x]. Say, Fitfunction_A = x and Fitfuction_B=F[x].
The fitting equation is "y = g0+F[t0/x]", and I tried with the following code, but I always got an error message. Could you be kind to tell me why this is not working? Any comments or suggestions will be very helpful for me.




In the NLSF. "Use Origin C" is on.

--------------
static double g0store, t0store;
Dataset dsX("Data1_x");//Dataset for fitting
Dataset dsscaleX("Data1_scaleX");//to get "t0/x"
Dataset dsExpv;
Curve fitFunction("fitFunction_A", "fitFunction_B");//Dataset for F[x]
int nSize= dsX.GetUpperBound();
if(g0!=g0store || t0!=t0store) {
dsscaleX = t0/ dsX;
for(int ii=0;ii<nSize; ii++) {
dsExpv[ii] = Curve_yfromX (&fitFunction, dsscaleX[ii]) ;
};
g0store=g0; t0store=t0;
};
y=g0+Data_table(x, &dsExpv, &dsX);
4   L A T E S T    R E P L I E S    (Newest First)
junsung Posted - 11/23/2006 : 5:03:50 PM
Dear Zachary and Mike

Thank you so much! It works very well now.
Mike Buess Posted - 11/17/2006 : 9:44:58 PM
Hi Jun Sung,

Origin C is case sensitive. Use exp(t1/x) instead of Exp(t1/x).

Mike Buess
Origin WebRing Member
junsung Posted - 11/17/2006 : 6:32:49 PM
Dear Zachary

Thank you so much!! I took your advice, and it works perfect!
If you don't mind, I'd like ask one more question about it.
Actually, my fitting function contains also the exponential function with two more parameters like "y=g0+F[t0/x]+g1*Exp[t1/x]".
I changed the last line in the program such as
y=g0+Data_table(x, &dsExpv, &dsX)+g1*Exp(t1/x);
but, it seems that Exp(x) function is not defined.
Could you be kind to tell me why it is so, and how to fix it?

best,

Jun Sung
zachary_origin Posted - 11/14/2006 : 9:36:25 PM
From the code, what I can find is that you defined a dataset "dsExpv" but did not attach it to an existing origin object. This is not valid in Origin C. So you need add a column and attach the column to dsExpv. The code can be changed as following. I have simulated it with F(x) = x^2, it works fine.


	static double g0store, t0store; 
	Dataset dsX("Data1_x");//Dataset for fitting 
	Dataset dsscaleX("Data1_scaleX");//to get "t0/x" 
	Dataset dsExpv("Data1_Expv"); //Manually add a column named Expv in Data1
	Curve fitFunction("fitFunction_A", "fitFunction_B");//Dataset for F[x] 
	int nSize= dsX.GetUpperBound(); 
	if(g0!=g0store || t0!=t0store) 
	{
		dsscaleX = t0/ dsX;
		dsExpv.SetSize(nSize); //It would be better to set the size of the dataset before using it to avoid some runtime error 
		for(int ii=0;ii<nSize; ii++) 
		{ 
			dsExpv[ii] = Curve_yfromX (&fitFunction, dsscaleX[ii]) ;
		} 
		g0store=g0; 
		t0store=t0; 
	} 
	y=g0+Data_table(x, &dsExpv, &dsX);

////End of function



Zachary
OriginLab Technical Services.

Edited by - zachary_origin on 11/14/2006 9:40:02 PM

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