| T O P I C R E V I E W |
| edwardclhuang |
Posted - 11/20/2011 : 2:31:17 PM
Origin Ver. and Service Release (Select Help-->About Origin): Origin8, SR4
Operating System:Win7, 64bit
Dear Sirs
I have to questions in this post. I have read some tutorials but still not so sure how I can proceed it. Please help me figure it out and thanks so much in advance.
1. I have a set of data and I would like to fit them with the following equation,
Independent Variables: x
Dependent Variables: y
Parameter Names: A0, A1, A2, A3, A4
It seems I can use "Labtalk" or "OriginC" to compute it, am I right? Please teach me how to do it.
2.After I get the best fitting results of A0~A4, how can I subtract this function with them in "Set Column Values "? I mean I have another set of data and I want to subtract the function as posted with known A0~A4.
Once again, any help or tutorial would be much appreciated.
|
| 2 L A T E S T R E P L I E S (Newest First) |
| edwardclhuang |
Posted - 11/23/2011 : 09:35:32 AM
Hello Hideo Fuji
Thanks for the help. Based on your suggestion, first of all I rewrite my function as following,
A0,A1,A2 are fitting parameters. If I replace A2/x = x and abbreviate the equation as following,
Then it comes a problem: I can not get A0, A1, and A2 apart from each other!!
Back to the first equation shown above, I am stuck on the upper bound in the integral(A2/x). Because it also shows in the formula for doing calculation. How can I do that by NAG library? I have tried to write this as
struct user
{
double A2c;
};
static double NAG_CALL f_callback(double x, Nag_User *comm)
{
struct user *sp = (struct user *)(comm->p);
double A2c;
A2c = sp->A2c;
return (A2c/x)^4 * exp(A2c/x) / ((exp(A2c/x)-1)^2);
}
How should I write in the "editable part" please? It seems I should replace "d01smc" formula by some other formulas, and what will be the proper formula?
I am really appreciated with your kindly help. |
| Hideo Fujii |
Posted - 11/21/2011 : 3:17:08 PM
Hi Edward,
The following tutorials may be helpful:
http://wiki.originlab.com/~originla/howto/index.php?title=Tutorial:Fitting_with_Integral_using_LabTalk_Function
http://wiki.originlab.com/~originla/howto/index.php?title=Tutorial:Fitting_with_Integral_using_NAG_Library
I think that you probably need to redefine the function by replacing the integral variable by e.g., z=A4/x .
Regarding the subtraction, you can subtract the data from your fitting result by "Analysis: Data Manipulation: Subtract Reference Data".
Note that in the latest Origin 8.6 version, you can directly define a fitting function which contains the integral in Fitting Function Builder. If you're interested in it, you can try the evaluation (demo) version of the latest Origin.
--Hideo Fujii
OriginLab |
|
|
