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funfine
USA
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 Posted - 07/30/2007 : 7:07:57 PM
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Origin Version (Select Help-->About Origin): Origin Pro7 Sr5
Operating System: Win Xp
Hi everyone,
I have met a new problem. I need to fit the data with exponential modified gaussian function chromatographic(called GaussMod in Origin). But actually the data is supposed to be the difference of two GaussMod function (GaussModA - GaussModB), where they share the A, xc and w, only different parameter t0. Does anyone know how to do this? I try to write my new function, but in the file of GaussMod function, there is no formula of GaussModA and I don't know how to write Non-numerical Integration. I am totally lost. Anybody can give a clue?
By the way, I think this function is the convolution of Gaussian and exponential decay function. Am I right? A, xc, w is the amplitude, center and width of Gaussian function and t0 is the time constant of exponential function, right?
Thank you all very much!
Ying
Edited by - funfine on 07/30/2007 7:09:16 PM |
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Mike Buess
USA
3037 Posts |
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funfine
USA
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Posted - 07/31/2007 : 08:57:26 AM
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Hi Mike,
I have seen the file. But I still have no idea how to access this function. Just as I said, there is no formula in this file, neither I know how to write integration function. I tried some expression as simple as y = GaussMod(y0, A, xc, w, t0) - GaussMod(0, A, xc, w, t1). But it cannot go through compiling. Origin C keep telling me the function GaussMod is not found.
Thank you very much!
Ying |
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Mike Buess
USA
3037 Posts |
Posted - 07/31/2007 : 09:26:33 AM
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First, the gaussmod function has six arguments... x and the five GaussMod parameters. Second, it is a LabTalk function and will not work directly in Origin C. You need to use something like this...
string strA;
strA.Format("gaussmod(%f,%f,%f,%f,%f,%f)",x,y0,A,xc,w,t0);
double dValA;
LT_evaluate(strA,&dValA);
// similar expression for gaussmodB -> dValB
y = dValA - dValB;
Mike Buess
Origin WebRing Member
Edited by - Mike Buess on 07/31/2007 09:28:37 AM
Edited by - Mike Buess on 07/31/2007 10:31:29 AM |
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NLSF : How to edit a built-in function