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sseb22
France
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 Posted - 03/12/2004 : 10:28:00 AM
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Hello
I have data coming from a interferometer. Thus, the graph plotted is oscillating at a quite high frequency and has multiple peaks.
I would now like to plot the wrap (the "envelop" as we say in France), that is the line connecting the tops of the peaks in order to get some kind of Gaussian curve from which I'll be able to obtain its characteristics.
Thank you
Seb
PS : I am using Origin 6.1 |
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sseb22
France
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Posted - 03/12/2004 : 10:41:05 AM
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| Actually, what I'd like to do is to fit a Gaussian curve on the graph but only using the coordinates of the peaks and not the entire data |
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sseb22
France
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Posted - 03/12/2004 : 11:00:44 AM
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i just tried it manually and it is exactly what i need
i just have hundreds of these graphs :/ |
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easwar
USA
1965 Posts |
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sseb22
France
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Posted - 03/12/2004 : 11:14:12 AM
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according to the examples, it should be perfect ! :D
but will it work on Origin 6.1 ? |
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easwar
USA
1965 Posts |
Posted - 03/12/2004 : 2:42:03 PM
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Hi Seb,
My apologies for not mentioning this before - that file from the File Exchange area works only in version 7.0 or higher since it uses Origin C code.
The algorithm used in finding the envelope points is as follows. You could try implementing this using LabTalk script which will then work in version 6.1:
1> divide the data into n bins, where n is a parameter passed to the function
2> in each bin, pick the top m points where m is also a parameter passed to the function
3> take all the points thus chosen, to give you the envelope points
4> you can then create a dataset that either just interpolates these points, or does spline fitting to them etc to create a smooth envelope curve
By varying parameters n and m, user can tune the function to return the optimum envelope curve for many different datasets.
Hope this helps.
Easwar
OriginLab.
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sseb22
France
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Posted - 03/15/2004 : 03:24:13 AM
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yes it does
i'll try and see how Labtalk works or do my own program
thanx
Seb |
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sseb22
France
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Posted - 03/17/2004 : 11:48:25 AM
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i did a program in C
am I allowed to display it here in order to get some help ? |
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sseb22
France
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Posted - 03/18/2004 : 05:19:32 AM
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that was it !!
my first program used the same algorithm as yours but only with the 3rd argument = 1
as you could see, it doesn't work
however, when 2 is entered, it works quite well
but i don't seem to make it work with the 3rd argument = 3. |
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sseb22
France
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Posted - 03/18/2004 : 07:42:19 AM
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sorry, my mistake
works also with 3 |
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The wrap of a fonction