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aeolian1
Germany
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 Posted - 02/19/2008 : 10:42:22 AM
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Origin Version (Select Help-->About Origin): 6.1
Operating System: XP
Hello,
I looked through related topics on the Forum, but couldn't find a recent answer that detailed the exact syntax I need:
I would like to simultaneously fit one data set to one fit function and a second data set to a second fit function, with 5 parameters shared between the functions. That is, I have a data set (x1,y1) which should be fitted to function f1, and a data set (x2,y2) which should be fitted to function f2, with parameters P1-P5 all shared; the x-values in each data set are totally different. Could you please tell me the *exact* syntax for defining such a "fitting conglomerate"? In the function definition section, I tried using
User-def. param. names: W1, W2, W3, W4, W5
Indep. variables: x1, x2
Dependent variables: y1, y2
Under the "form" I selected "Equations" and typed in the following function definitions:
y1 = f1(x1, W1, W2, W3, W4, W5);
y2 = f2(x2, W1, W2, W3, W4, W5)
but this gave the error "Function definition is incorrect." Could you please tell me where I am going astray?
Thank you very much!!
P.S. (not as urgent a question) I noticed a while back that once Origin generates more than 99 simulated curves of the type "nlsf_b", things seem to go haywire (and that deleting the generated curves doesn't help, since Origin keeps numbering sequentially). Wondering along the same lines, will I have a problem once I try to define user100? I currently have 90-some user-defined functions, so this will happen soon; unfortunately, I need all of these functions... |
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Echo_Chu
China
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Posted - 02/19/2008 : 9:01:47 PM
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Hi,
x1, x2 and y1, y2 are our system variables. They can not be used as independent/dependent variables in fitting function.
Could you try xx1, xx2, yy1 and yy2 insteadly?
Echo
OriginLab Corp |
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suikou
Brazil
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Posted - 03/02/2008 : 8:08:56 PM
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| You may try Auto2Fit (1stOpt), it is quite easy to solve the problems like "shared params". |
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Fitting 2 eqns to 2 indep.data sets; shared params