Solving Exponential equation with data
조회 수: 2 (최근 30일)
이전 댓글 표시
Dear sir,
I want to find four unknowns(a,b,c,d) which would fit with the model as y = a*(1-exp(-b*x)) + c*(exp(d*x)-1).
I am attaching data herewith. Please help me in chosing initial guess for unknowns.
Please provide steps and code in case for me to get started and able to fit it with the model.
Thank you
댓글 수: 2
Alex Sha
2020년 9월 11일
1:
a -0.00353320943950358
b -0.00183821185934112
c -0.0092638389118119
d -0.00950908245890883
2:
a 0.00926383877006205
b 0.00950908267448672
c 0.00353320959565315
d 0.0018382118314121
채택된 답변
Alan Stevens
2020년 9월 10일
Try
a = 0.0093; b = 0.0095; c = 0.0035; d = 0.00185;
f = a*(1 - exp(-b*x)) + c*(exp(d*x) - 1);
plot(x,y,'o',x,f),grid
xlabel('x'),ylabel('y')
legend('data','function')
to get
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/358837/image.jpeg)
However, the curve fitting toolbox shoud get an even better fit (I don't have the curve fitting toolbox, so did a rough fit outside of Matlab).
댓글 수: 3
Alan Stevens
2020년 9월 11일
As I said, because I don't have MATLAB's curve fitting toolbox I used another piece of software (Mathcad) to do the fit. I then rounded the numbers to the values I listed in my earlier reply.
추가 답변 (0개)
참고 항목
카테고리
Help Center 및 File Exchange에서 Fit Postprocessing에 대해 자세히 알아보기
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!