| Author |
 Topic  |
|
|
kemeyer
39 Posts |
 Posted - 07/15/2010 : 10:20:26 AM
|
Origin Ver. and Service Release : 8.1 SR1
Operating System: Vista
Hi,
I am trying to define a fitting equation for some data I have. The equation I am trying to add is called the Sellmeier Equation, and the form of it that I wish to use is:
n^2= A + B*Lambda^2/(Lambda^2-C) + D*Lambda^2/(Lambda^2-E)
When I tried to define the equation using the fitting function organizer, I typed it in as:
y = sqrt(A + B*Lambda^2/(Lambda^2-C) + D*Lambda^2/(Lambda^2-E))
and it compiled in the code builder. For the independent variables I put Y, for the dependent variables I put Lambda, and for the parameters I put A, B, C, D, E.
When I ran the fitting function to fit my data, I didn't get a fit. It said that I need to initialize my variables, so I went back and under the parameter tab I entered values into the value boxes that would be close. Also, I checked the data delection under the settings tab to ensure it was using the data properly. I still can not get my function to work...could someone help me? This is the data I have...
Lambda y
0.4046 2.0927
0.42 2.0794
0.44 2.0638
0.46 2.0506
0.48 2.0399
0.5 2.0305
0.52 2.0226
0.54 2.0159
0.56 2.0097
0.58 2.0046
0.6 2.0000
0.62 1.9959
0.64 1.9923
0.66 1.9889
0.68 1.9859
0.7 1.9832
0.75 1.9774
0.8 1.9727
0.85 1.9688
0.9 1.9655
0.95 1.9627
1 1.9603
1.05 1.9582
1.1 1.9565
1.15 1.9549
1.2 1.9534
1.25 1.952
1.3 1.9506
1.35 1.9493
1.4 1.9482
And these were the values for A, B, C, D,and E that were calculated by another method.
A=2.3288, B=1.4519, C=0.048025, D=1.7045, E=158.08
Thanks,
Katie |
|
|
kemeyer
39 Posts |
Posted - 07/15/2010 : 10:25:57 AM
|
Sorry, the data looks really bad there...I'll post it this way instead.
Lambda
0.4046
0.42
0.44
0.46
0.48
0.5
0.52
0.54
0.56
0.58
0.6
0.62
0.64
0.66
0.68
0.7
0.75
0.8
0.85
0.9
0.95
1
1.05
1.1
1.15
1.2
1.25
1.3
1.35
1.4
y
2.0927
2.0794
2.0638
2.0506
2.0399
2.0305
2.0226
2.0159
2.0097
2.0046
2.0000
1.9959
1.9923
1.9889
1.9859
1.9832
1.9774
1.9727
1.9688
1.9655
1.9627
1.9603
1.9582
1.9565
1.9549
1.9534
1.952
1.9506
1.9493
1.9482
|
 |
|
|
kemeyer
39 Posts |
Posted - 07/15/2010 : 11:05:26 AM
|
| Nevermind, I figured it out. I messed up the dependent and independent variables. |
|
|
| |
Topic |
|
|
|
User defined: fitting equations