Fitting 8 equations simultaneously with three parameters

36 次查看（过去 30 天）
Vahid Askarpour
Vahid Askarpour 2025-9-19，17:46
评论： Vahid Askarpour 2025-9-19，21:08
I have 8 equations each with three parameters (A, B, and C) to be fitted. For example,
Eq. 1: 2A+3B+5C-1=0
Eq. 2: -5A+2B-10C+12=0 and so on
I would like to fit the three parameters so that all the 8 equations almost hold simultaneously. Having looked at other posts, it seems that lsqnonlin may be the right choice. I am not looking for the actual solution but I would appreciate a yes or no to the use of lsqnonlin for this problem.
Thanks,
Vahid

请先登录，再回答此问题。

采纳的回答

Torsten
Torsten 2025-9-19，17:49
编辑：Torsten 2025-9-19，17:50
If all 8 equations are linear in the fitting parameters like in your example from above, "lsqlin" instead of "lsqnonlin" would be the code to use. If this is not the case, yes: use "lsqnonlin".
  2 个评论
Vahid Askarpour
Vahid Askarpour 2025-9-19，18:09
Thanks Torsten for the tip. They are all linear and I will be using lsqlin.
Torsten
Torsten 2025-9-19，19:40
编辑：Torsten 2025-9-19，20:03
Ran in:
If there are no constraints on the solution parameters, @Star Strider 's suggestion is also possible to use:
% Eq. 1: 2A+3B+5C-1=0
% Eq. 2: -5A+2B-10C+12=0
% Eq. 3: 9A-B+2C+5=0
% Eq. 4: 4A-7B+6C-13=0
ABC = lsqlin([2 3 5; -5 2 -10; 9 -1 2; 4 -7 6],[1; -12; -5; 13])
ABC = 3×1
-1.0118 -1.2492 1.4242
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
ABC = [2 3 5; -5 2 -10; 9 -1 2; 4 -7 6] \ [1; -12; -5; 13]
ABC = 3×1
-1.0118 -1.2492 1.4242
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>

请先登录，再进行评论。

更多回答（1 个）

Star Strider
Star Strider about 24 hours 前
Ran in:
You might be able to use the mldivide, \ function --
Example --
% Eq. 1: 2A+3B+5C-1=0
% Eq. 2: -5A+2B-10C+12=0
% Eq. 3: 9A-B+2C+5=0 % <- ADDED
ABC = [2 3 5; -5 2 -10; 9 -1 2] \ [1; -12; -5]
ABC = 3×1
-1.0284 -1.3785 1.4385
<mw-icon class=""></mw-icon>
<mw-icon class=""></mw-icon>
fprintf('\nA = %9.5f\nB = %9.5f\nC = %9.5f\n',ABC)
A = -1.02839 B = -1.37855 C = 1.43849
.
  1 个评论
Vahid Askarpour
Vahid Askarpour 2025-9-19，21:08
Thank you Star Strider and Torsten for your comments. I used both your suggestions and I get exactly the same answer.
Cheers,
Vahid

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Linear Least Squares 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by