Deconvolution for solving nonlinear system

2018 4 4
1 个回答
更新时间：2018 4 5
2 次查看（30 天）

0 个投票

Dear all,
I have a question on solving nonlinear equations with convolutions. Please help me with codes, ideas or procedures. Here are the equations. Where V,Z11,Z21,Z12,Z22 are known and V is an array of numbers with size(1,100), Z11,Z21,Z12,Z22 are array of complex numbers with same size as V. How can I calculate Vx and Vy? Thank you very very much. Looking forward to your reply.
Best Regards
Zhifei

2 个评论
显示 无 隐藏 无

Matt J
Matt J 2018-4-4
What are I1 and I2? Known? Unknown?
zhifei xu
zhifei xu 2018-4-4
I1 and I2 are unknown, you have to substitue them to the first 2 equations.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Matt J
Matt J 2018-4-4

0 个投票

Seems like a good candidate for FSOLVE.

6 个评论
显示 4更早的评论 隐藏 4更早的评论

zhifei xu
zhifei xu 2018-4-4
But the conv and deconv function does not support symbols
Matt J
Matt J 2018-4-4
编辑：Matt J 2018-4-4
FSOLVE is not in the Symbolic Math Toolbox. It is a purely numerical solver. It is doubtful (to me) that the equations you've shown have a closed form symbolic solution.
zhifei xu
zhifei xu 2018-4-4
编辑：Matt J 2018-4-4
Thanks for your response. The results of my equations will be an array of complex numbers(I guess deconvolved results).I tried to use fsolve to solve a simple deconvolution example.It gives me the error.I do not know why. "fsolve stopped because the problem appears regular as measured by the gradient, but the vector of function values is not near zero as measured by the default value of the function tolerance." And my code is below:
options=optimset('Algorithm','Levenberg-Marquardt');
[x,fval] = fsolve(@g,0,options);
function F=g(x)
u = [1 0 1 1 ];
w = [2 7 2 7];
t=[4 16 9 9]; %the convolution result of u and w
F =conv(u,x,'same')-t;
end
Matt J
Matt J 2018-4-4
You need to run as follows,
options=optimset('Algorithm','Levenberg-Marquardt');
[x,fval] = fsolve(@g,[0,0,0,0],options)
function F=g(x)
u = [1 0 1 1 ];
t=[4 16 9 9]; %the convolution result of u and w
F =conv(u,x,'same')-t;
end
zhifei xu
zhifei xu 2018-4-4
Thank you very much, I will try to apply this to solve my equations, i will let you know if i succeed. Thank you so much. Have a nice day!!
zhifei xu
zhifei xu 2018-4-5
@Matt J Hello,
I tried with my equations,however, the results are not reliable. and then I tried with another codes with 2 variables. Matlab said no solutions：No solution found.
fsolve stopped because the last step was ineffective. However, the vector of function values is not near zero, as measured by the default value of the function tolerance.
criteria details here is my code: clc close all a1=zeros(1,4); a2=zeros(1,4); options=optimset('Algorithm','Levenberg-Marquardt'); [x,fval] = fsolve(@g,[a1;a2],options); function F=g(x) u = [1 0 1 1 ]; w = [2 7 2 7]; q=[2 2 1 4]; l=[3 4 4 5]; t=[4 16 9 9]; %the convolution result of u and w tt=[21 37 38 31];%the convolution result of q and l F =[conv(u,x(1),'same')-t;conv(q,x(2),'same')-x(1)-tt]; end

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Systems of Nonlinear Equations 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