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chris_1877
Austria
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 Posted - 07/31/2007 : 02:48:46 AM
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Origin Version (Select Help-->About Origin): 7.0303
Operating System: WinXP
Hi there!
I got another problem with origin, when using the advanced fitting tool (Strg+Y) with the function Extreme (located in peak functions). Normally I use the fitting tool without problems, sometimes only the parameters are hard to initialize.
In this case the data (residence time spectra), which should be fitted is shifted while the fitting process. This means that before fitting, my data (3 curves, each consist from about 15 or more data points) start at different points, after fitting they all start at the same value. Is this due to the function Extreme itself, or am I doing something wrong?
Thanks for the help,
Chris |
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Fay_Guo
China
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Posted - 07/31/2007 : 04:55:35 AM
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Hi Chirs:
Could you please send your data to tech@originlab.com and describe your steps in detail, then we can have a try?
Thanks
Fay
Originlab Tech Service
Edited by - Fay_Guo on 07/31/2007 05:38:42 AM |
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chris_1877
Austria
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Posted - 07/31/2007 : 05:33:30 AM
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Hi Fay!
Here are the three data sets (each x is t/min and y colour/a.u.).
Thank you for your help.
Chris
25,6 -1,5 23,7 -3,59 13,9 -2,48
28,59 -13,7 26,69 -27,53 16,89 -21,94
31,59 -26,07 29,69 -32,35 19,89 -28,58
34,58 -25,76 32,68 -29,85 22,88 -23,71
37,58 -20,73 35,68 -23,56 25,88 -15,67
40,57 -14,02 38,67 -19,14 28,87 -10,73
43,56 -9,75 41,66 -13,07 31,86 -6,76
46,56 -5,83 44,66 -10,38 34,86 -5,71
49,55 -4,52 47,65 -7,97 37,85 -4,15
52,55 -3,41 50,65 -6,29 40,85 -2,92
55,54 -3,09 53,64 -4,82 43,84 -2,24
58,53 -2,01 56,63 -3,96 46,83 -2,7
61,53 -1,5 59,63 -3,06 49,83 -1,67
64,52 -2,29 62,62 -3,07 52,82 -0,97
65,62 -2,72 55,82 -0,93
68,61 -2,84 58,81 -2,01
71,6 -2,12 61,8 -1,36
74,6 -1,49 64,8 -0,85
77,59 -2,32 67,79 -2,02
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Mike Buess
USA
3037 Posts |
Posted - 07/31/2007 : 09:02:47 AM
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Hi Chris,
The Extreme function doesn't work for your data because your peaks are upside down. Multiply all y columns by -1 and try again.
...Looks like the reason is not because your peaks are inverted but because they are incomplete (truncated on the left). Even after inverting peaks 2 and 3 they are very difficult to fit. If you add a couple points on the left to help define the baseline then the peaks will be much easier to fit.
Mike Buess
Origin WebRing Member
Edited by - Mike Buess on 07/31/2007 10:24:18 AM |
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chris_1877
Austria
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Posted - 07/31/2007 : 10:55:07 AM
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Hi Mike!
Thank you for the help.
Inverting the y-Data was not successful, but when adding some points on the left side, the fit worked well.
Thanks a lot to you and Fay!
Chris |
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problem with data fitting