| T O P I C R E V I E W |
| tony_lincoln |
Posted - 02/09/2009 : 9:32:40 PM
Dear Madam/Sir,
I tried to fit curve 1 using single exponential fitting (y=a*exp(b*x) + c) in Origin 8. However, in different computers, I got the different b value: 0.07427 or 0.04141.
Then I used another two softwares, ZunZun and GraphPad, I also got different b value, either .07427 or 0.04141. So I am really confused --- which one I shoud choose? What could be the reason to have these two different values?
Curve 1, 2 and 3 have the same y values, I just changed did linear transformation and changed x value in curve 1, and changed it into curve 2 and 3. Curve 1 is the original curve. Another question is, are these 3 curves still the SAME curve?
GraphPad gave me same b value for these 3 curves, but Origin gave me either .07427 or 0.04141 for these 3 curves in 3 different computers.
I really appreciate it if anyone can show me any hints!
Thanks.
Curve 1:
24.0860 0.929920
24.6660 0.916290
25.2230 0.901922
25.7400 0.942780
26.3510 0.875073
26.8660 0.955152
27.4850 0.826904
28.0070 0.904872
28.6030 0.879004
29.1490 0.919224
29.6950 0.899116
30.2310 1.00000
30.8100 0.829106
31.3660 0.786188
31.9380 0.852532
32.4600 0.859475
33.0550 0.861591
33.5650 0.848461
34.1790 0.942449
34.7020 0.901296
35.2950 0.994809
35.8140 0.864114
36.4080 0.847948
36.9330 0.796047
37.5010 0.880572
38.0540 0.914439
38.6380 0.779416
39.1860 0.897249
39.7330 0.857322
40.2730 0.792637
40.8580 0.837627
41.3960 0.866486
41.9850 0.787097
42.5140 0.866246
43.1150 0.804120
43.6340 0.835493
44.2290 0.872154
44.7700 0.819632
45.3710 0.835273
45.8930 0.850420
46.5060 0.812996
47.0240 0.887566
47.5950 0.783647
48.1390 0.848138
48.7120 0.852972
49.2500 0.897498
49.7980 0.959756
50.3470 0.924552
50.9310 0.903747
51.4580 0.928523
52.0740 0.776699
52.5940 0.737524
53.1910 0.915994
53.7260 0.906656
54.3220 0.874060
54.8500 0.806015
55.4410 0.833587
55.9770 0.854967
56.5690 0.697498
57.1100 0.810998
57.6790 0.787988
58.2250 0.808483
58.7690 0.795053
59.3120 0.801478
59.9100 0.838632
60.4540 0.811416
61.0310 0.780859
61.5430 0.879334
62.1450 0.846360
62.6640 0.801117
63.2640 0.892933
63.7930 0.851976
64.3900 0.904398
64.9140 0.870151
65.5130 0.840888
66.0320 0.911335
66.6120 0.913124
67.1470 0.881224
67.7230 0.827847
68.2680 0.890090
68.8190 0.829092
69.3600 0.863297
69.9510 0.828419
70.4610 0.935923
71.0620 0.819145
71.5870 0.915325
72.1850 0.910613
72.6930 0.957231
73.3030 0.849726
73.8040 0.918761
74.4000 0.846629
74.9330 0.784890
75.5470 0.927283
76.0650 0.795014
76.6370 0.835413
77.1870 0.767532
77.7600 0.849958
78.3030 0.852627
78.8520 0.812643
79.3990 0.875839
79.9950 0.851806
80.5090 0.853117
81.1080 0.789958
81.6330 0.836185
82.2370 0.710101
82.7710 0.738166
83.3740 0.737436
83.8970 0.861690
84.5090 0.825159
85.0380 0.877351
85.6130 0.848397
86.1530 0.820122
86.7320 0.827983
87.2790 0.785532
87.8320 0.797776
88.3810 0.807236
88.9610 0.919723
89.5080 0.786163
90.0860 0.899443
90.6060 0.862198
91.2090 0.875951
91.7280 0.826531
92.3280 0.848424
92.8310 0.696854
93.4300 0.864295
93.9420 0.887419
94.5610 0.872820
95.0790 0.899159
95.6580 0.816256
96.1910 0.786831
96.7590 0.757777
97.3050 0.814912
97.8750 0.807445
98.4210 0.809484
99.0070 0.819021
99.5250 0.844852
100.124 0.829012
100.632 0.921174
101.237 0.740333
101.749 0.937426
102.372 0.910489
102.948 0.769717
103.546 0.812040
104.062 0.962371
104.674 0.879244
105.211 0.822913
105.796 0.842098
106.340 0.893583
106.894 0.827722
107.433 0.914815
108.018 0.915150
108.536 0.800499
109.299 0.721179
109.805 0.773495
110.955 0.812093
111.555 0.862583
112.081 0.884459
112.679 0.784145
113.222 0.813928
113.798 0.771603
114.349 0.786055
114.906 0.757662
115.446 0.762902
116.023 0.923205
116.540 0.830537
117.144 0.911862
117.662 0.799846
118.259 0.875198
118.770 0.878877
119.405 0.943356
119.975 0.916483
120.592 0.827536
121.106 0.750521
121.677 0.814044
122.219 0.722055
122.799 0.704069
123.340 0.781803
123.890 0.834400
124.427 0.896388
125.014 0.855558
125.553 0.705719
Curve 2:
1 0.92992
2 0.91629
3 0.901922
4 0.94278
5 0.875073
6 0.955152
7 0.826904
8 0.904872
9 0.879004
10 0.919224
11 0.899116
12 1
13 0.829106
14 0.786188
15 0.852532
16 0.859475
17 0.861591
18 0.848461
19 0.942449
20 0.901296
21 0.994809
22 0.864114
23 0.847948
24 0.796047
25 0.880572
26 0.914439
27 0.779416
28 0.897249
29 0.857322
30 0.792637
31 0.837627
32 0.866486
33 0.787097
34 0.866246
35 0.80412
36 0.835493
37 0.872154
38 0.819632
39 0.835273
40 0.85042
41 0.812996
42 0.887566
43 0.783647
44 0.848138
45 0.852972
46 0.897498
47 0.959756
48 0.924552
49 0.903747
50 0.928523
51 0.776699
52 0.737524
53 0.915994
54 0.906656
55 0.87406
56 0.806015
57 0.833587
58 0.854967
59 0.697498
60 0.810998
61 0.787988
62 0.808483
63 0.795053
64 0.801478
65 0.838632
66 0.811416
67 0.780859
68 0.879334
69 0.84636
70 0.801117
71 0.892933
72 0.851976
73 0.904398
74 0.870151
75 0.840888
76 0.911335
77 0.913124
78 0.881224
79 0.827847
80 0.89009
81 0.829092
82 0.863297
83 0.828419
84 0.935923
85 0.819145
86 0.915325
87 0.910613
88 0.957231
89 0.849726
90 0.918761
91 0.846629
92 0.78489
93 0.927283
94 0.795014
95 0.835413
96 0.767532
97 0.849958
98 0.852627
99 0.812643
100 0.875839
101 0.851806
102 0.853117
103 0.789958
104 0.836185
105 0.710101
106 0.738166
107 0.737436
108 0.86169
109 0.825159
110 0.877351
111 0.848397
112 0.820122
113 0.827983
114 0.785532
115 0.797776
116 0.807236
117 0.919723
118 0.786163
119 0.899443
120 0.862198
121 0.875951
122 0.826531
123 0.848424
124 0.696854
125 0.864295
126 0.887419
127 0.87282
128 0.899159
129 0.816256
130 0.786831
131 0.757777
132 0.814912
133 0.807445
134 0.809484
135 0.819021
136 0.844852
137 0.829012
138 0.921174
139 0.740333
140 0.937426
141 0.910489
142 0.769717
143 0.81204
144 0.962371
145 0.879244
146 0.822913
147 0.842098
148 0.893583
149 0.827722
150 0.914815
151 0.91515
152 0.800499
153 0.721179
154 0.773495
155 0.812093
156 0.862583
157 0.884459
158 0.784145
159 0.813928
160 0.771603
161 0.786055
162 0.757662
163 0.762902
164 0.923205
165 0.830537
166 0.911862
167 0.799846
168 0.875198
169 0.878877
170 0.943356
171 0.916483
172 0.827536
173 0.750521
174 0.814044
175 0.722055
176 0.704069
177 0.781803
178 0.8344
179 0.896388
180 0.855558
181 0.705719
Curve 3.
0 0.92992
0.58 0.91629
1.137 0.901922
1.654 0.94278
2.265 0.875073
2.78 0.955152
3.399 0.826904
3.921 0.904872
4.517 0.879004
5.063 0.919224
5.609 0.899116
6.145 1
6.724 0.829106
7.28 0.786188
7.852 0.852532
8.374 0.859475
8.969 0.861591
9.479 0.848461
10.093 0.942449
10.616 0.901296
11.209 0.994809
11.728 0.864114
12.322 0.847948
12.847 0.796047
13.415 0.880572
13.968 0.914439
14.552 0.779416
15.1 0.897249
15.647 0.857322
16.187 0.792637
16.772 0.837627
17.31 0.866486
17.899 0.787097
18.428 0.866246
19.029 0.80412
19.548 0.835493
20.143 0.872154
20.684 0.819632
21.285 0.835273
21.807 0.85042
22.42 0.812996
22.938 0.887566
23.509 0.783647
24.053 0.848138
24.626 0.852972
25.164 0.897498
25.712 0.959756
26.261 0.924552
26.845 0.903747
27.372 0.928523
27.988 0.776699
28.508 0.737524
29.105 0.915994
29.64 0.906656
30.236 0.87406
30.764 0.806015
31.355 0.833587
31.891 0.854967
32.483 0.697498
33.024 0.810998
33.593 0.787988
34.139 0.808483
34.683 0.795053
35.226 0.801478
35.824 0.838632
36.368 0.811416
36.945 0.780859
37.457 0.879334
38.059 0.84636
38.578 0.801117
39.178 0.892933
39.707 0.851976
40.304 0.904398
40.828 0.870151
41.427 0.840888
41.946 0.911335
42.526 0.913124
43.061 0.881224
43.637 0.827847
44.182 0.89009
44.733 0.829092
45.274 0.863297
45.865 0.828419
46.375 0.935923
46.976 0.819145
47.501 0.915325
48.099 0.910613
48.607 0.957231
49.217 0.849726
49.718 0.918761
50.314 0.846629
50.847 0.78489
51.461 0.927283
51.979 0.795014
52.551 0.835413
53.101 0.767532
53.674 0.849958
54.217 0.852627
54.766 0.812643
55.313 0.875839
55.909 0.851806
56.423 0.853117
57.022 0.789958
57.547 0.836185
58.151 0.710101
58.685 0.738166
59.288 0.737436
59.811 0.86169
60.423 0.825159
60.952 0.877351
61.527 0.848397
62.067 0.820122
62.646 0.827983
63.193 0.785532
63.746 0.797776
64.295 0.807236
64.875 0.919723
65.422 0.786163
66 0.899443
66.52 0.862198
67.123 0.875951
67.642 0.826531
68.242 0.848424
68.745 0.696854
69.344 0.864295
69.856 0.887419
70.475 0.87282
70.993 0.899159
71.572 0.816256
72.105 0.786831
72.673 0.757777
73.219 0.814912
73.789 0.807445
74.335 0.809484
74.921 0.819021
75.439 0.844852
76.038 0.829012
76.546 0.921174
77.151 0.740333
77.663 0.937426
78.286 0.910489
78.862 0.769717
79.46 0.81204
79.976 0.962371
80.588 0.879244
81.125 0.822913
81.71 0.842098
82.254 0.893583
82.808 0.827722
83.347 0.914815
83.932 0.91515
84.45 0.800499
85.213 0.721179
85.719 0.773495
86.869 0.812093
87.469 0.862583
87.995 0.884459
88.593 0.784145
89.136 0.813928
89.712 0.771603
90.263 0.786055
90.82 0.757662
91.36 0.762902
91.937 0.923205
92.454 0.830537
93.058 0.911862
93.576 0.799846
94.173 0.875198
94.684 0.878877
95.319 0.943356
95.889 0.916483
96.506 0.827536
97.02 0.750521
97.591 0.814044
98.133 0.722055
98.713 0.704069
99.254 0.781803
99.804 0.8344
100.341 0.896388
100.928 0.855558
101.467 0.705719
Thanks a lot!
Tony |
| 4 L A T E S T R E P L I E S (Newest First) |
| Deanna |
Posted - 02/10/2009 : 9:51:18 PM
The 3 curves are different, because the relationship betwen X and Y is not linear in the exponential fitting function (y=a*exp(b*x) + c). Changing X will yield different fitted parameters.
By using the ExpDEC1 function, which is built-in, I got:
A1 = 0.48888 for the first curve;
A1 = 0.0851 for the second curve;
A1 = 0.08182 for the thrid curve.
Deanna
OriginLab Technical Services |
| tony_lincoln |
Posted - 02/10/2009 : 11:25:33 AM
Thanks for the quick reply. I really appreciate it.
One question to Deanna:
Did you try ALL 3 curves? In my computer, for curve 2, I got 0.04141. For curve 1 and 3, I got 0.07427. So I should use 0.07427 I think.
easwar's suggestion sounds reasonable. I should try to set a higer max iteration number.
Thanks a lot
Tony |
| easwar |
Posted - 02/10/2009 : 10:44:00 AM
Hi,
Also note that the fitter has maximum iteration and tolerance settings. The iterative procedure stops when tolerance is met (chi-sqr does not reduce any further within speficied tolerance) OR if maximum iterations is met.
So when you get different values, it is possible the max iteration or tolerance values were different on these machines, so please check that to see they are same.
You can change these settings such as setting a higer max iteration number. The controls are under teh Settings->Advanced->Fit Control branch (assuming you are using version 8) of the fitter tool.
Easwar
OriginLab |
| Deanna |
Posted - 02/10/2009 : 05:02:20 AM
I got the same B value (.07427) on multiple computers. I am not sure why this happens to you. Could it be caused by different initial values? Initial values are values assigned to the parameters when the fitting begins. It could also be caused by different settings.
Please try to use the ExpDEC1 built-in function to test on your computers and tell us whether the results are the same.
Also, I suggest patching to SR4, which is the latest SR.
Deanna
OriginLab Technical Services |
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