| T O P I C R E V I E W |
| lsanii |
Posted - 11/15/2004 : 2:50:00 PM
I have absorbance data with two peaks, and I'm trying to fit the two components to two Gaussians. I've tried just doing analysis->fit guassian and all it does it fit one of the peaks and ignores the other.
I tried doing analysis->fit multi peaks->Guassian but then I don't know how to proceed from here and I can't find anything in the help menus to guide me. Please help!
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| 5 L A T E S T R E P L I E S (Newest First) |
| Laurie |
Posted - 11/15/2004 : 3:49:53 PM
We got your data...thank you.
In Graph1 of your project, you have two datasets plotted. In order to fit the 2 datasets simultaneously to a gaussian function, you will need to select Analysis:Nonlinear Curve Fit:Advanced Fitting tool.
1. Function:Select will allow you to select the Gaussian function.
2. Action:Dataset will allow you to check the "Fit Multiple Datasets" checkbox, and then assign from Available Datasets the y1, x1 and y2, x2 variables. You can also specify the Parameters to share.
3. Action:Fit to fit the data.
I am also sending you a followup email.
OriginLab Technical Support |
| lsanii |
Posted - 11/15/2004 : 3:30:42 PM
Thanks, just sent the data to the address.
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| easwar |
Posted - 11/15/2004 : 3:25:21 PM
Hi,
Please send the data/OPJ to tech@originlab.com and in your e-mail refer to this forum post.
Easwar
OriginLab
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| lsanii |
Posted - 11/15/2004 : 3:16:50 PM
Yes, I am seeing the secondary dialog boxes but getting confused on what to do. Maybe there isn't enough spetral overlap for the function to work right. Can I send you my data so you can see what I'm talking about?
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| easwar |
Posted - 11/15/2004 : 3:05:46 PM
Hi,
Not clear if you are trying to do this manually or programmatically...
If manually, you can invoke the Fit Multi Peaks->Gaussian menu item and then additional dialogs should come up that ask you for how many peaks you have, and an interactive cursor that lets you pick the initial peak position on the graph etc. If you are not seeing the secondary dialogs etc when operating manually, contact tech support to figure out what is going on.
Now, if you are planning to do this programmatically, you need to access the NLSF object and its properties. This can be done via LabTalk script or Origin C. For built-in peak functions such as Gaussian, there is a replicate property that can be used to set the number of replicates (peaks) in your data. You will then need to programmatically assign initial guess values and then do the fit. You can look up the NLSF object under the LabTalk documentation to see what property to set etc.
Easwar
OriginLab
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