# Example 29 - Nonlinear Regression
# Pressure Data
# Verified Solution: A=5.76735, B=677.094, C=153.885
# Ref.: Comput. Appl. Eng. Educ. 6: 173, 1998
[
TC P
-36.7 1
-19.6 5
-11.5 10
-2.6 20
7.6 40
15.4 60
26.1 100
42.2 200
60.6 400
80.1 760
]
logP=log(P)
# nlinfit <y> = <f(x1,x2,x3,...,m1,m2,m3...)>
nlinfit logP = A-B/(C+TC)
# Initial guess of the regression model variables
m(A)= 8.752
m(B)= 2035
m(C)=273
logP = A-B/(C+TC)
| Variable |
Initial guess |
Value |
95% confidence |
| A |
8.752 |
5.7673466 |
0.15208443 |
| B |
2035 |
677.09404 |
48.15906 |
| C |
273 |
153.88537 |
5.6870892 |
| R^2 |
R^2adj |
Rmsd |
Variance |
| 0.9996879 |
0.9995987 |
0.0047228 |
0.0003186 |
Nonlinear Regression Plot

Nonlinear Regression Residuals Plot

Source data points and calculated data points
| |
TC |
logP |
logP calc |
Delta logP |
| 1 |
-36.7 |
0 |
-0.01062733 |
0.01062733 |
| 2 |
-19.6 |
0.69897 |
0.7251442 |
-0.02617419 |
| 3 |
-11.5 |
1 |
1.0119843 |
-0.01198433 |
| 4 |
-2.6 |
1.30103 |
1.2917386 |
0.00929143 |
| 5 |
7.6 |
1.60206 |
1.5744341 |
0.02762584 |
| 6 |
15.4 |
1.7781513 |
1.767627 |
0.01052429 |
| 7 |
26.1 |
2 |
2.0054074 |
-0.00540739 |
| 8 |
42.2 |
2.30103 |
2.3142893 |
-0.01325929 |
| 9 |
60.6 |
2.60206 |
2.6105158 |
-0.00845581 |
| 10 |
80.1 |
2.8808136 |
2.8736015 |
0.00721212 |
General
| Algorithm |
LM |
| Sample size |
10 |
| Model vars |
3 |
| Indep vars |
1 |
| Iterations |
24 |
| Max iterations |
64 |