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dbisping
Germany
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 Posted - 03/08/2004 : 04:09:21 AM
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Hi everbody!
I searched the net, this forum and the Origin Handbook, but nothing could answer my question, perhaps you can.
With the Calculus -> Integrate Function in Origin 6.0 I can not only integrate but this function also delivers me the peak height, peak position and FWHM (Full Width of Half Maximum). For understanding the datas Origin gives to me I would like to know how this works, so what the mathematical algorithm of this peak determination function is.
Thanks a lot for any help!
Dirk Bisping |
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Gary Lane
USA
150 Posts |
Posted - 03/10/2004 : 10:09:32 AM
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Hi Dirk,
The Calculus|Integrate menu command computes "peak" in the sense of "maximum" and not in the sense of "peak finding." So, Peak Height means the maximum Y value, Peak Position means the X value at the maximum Y value, and FWHM means the full width (change in X) at half the maximum Y value (in your mind draw a horizontal line at 1/2 the maximum Y value and calculate the change in X between where the horizontal line intersects the data curve).
To "Find Peaks" try the Tools|Pick Peaks or Tools|Baseline Origin menu items. You might also try the PFM (Peak Fitting Module) which is sold separately as a module in Origin 6.0 but which is included with OriginPro 7.5 (our current release version).
I hope this is helpful.
Gary
OriginLab
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Gary Lane
USA
150 Posts |
Posted - 03/11/2004 : 10:55:39 AM
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Hi,
I apologize but I may be mistaken about my explanation for FWHM. We are workinging on finding a better answer and will post soon.
Gary
OriginLab
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Gary Lane
USA
150 Posts |
Posted - 03/11/2004 : 2:06:36 PM
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Hi again,
After checking the code it appears that when calculating FWHM we follow the procedure that I described in my post above but we do not interpolate if the X at half maximum values do not fall exactly on an X data value....we use the nearest X data value in the X dataset.
We will reseach and are considering whether or not to linearly interpolate in future versions. All feedback is welcome.
Gary
OriginLab
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Mike Buess
USA
3037 Posts |
Posted - 03/11/2004 : 2:29:13 PM
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Hi Gary,
I vote for interpolation. It can be important when there are only a few points in the peak. Interpolation was used even when peaks were analyzed on graph paper and should be taken for granted on a computer.
Mike Buess
Origin WebRing Member |
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cpyang
USA
1406 Posts |
Posted - 03/25/2004 : 4:20:50 PM
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This bug is trackered as 6171
CP
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qa
China
10 Posts |
Posted - 03/31/2004 : 03:59:18 AM
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Hi, all
#6171 has been fixed.
Thanks
Branda |
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Mathematical Algorithm of Peak Determination