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Solving Non-linear equations

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Hazem
Hazem 2015-8-5
评论： Hazem 2015-8-6
Hi !
I am trying to solve this set of non-linear equations using Matlab ... and i am not getting any solution
they are 3 equations with three variables as follow:
-1.63-10.6*cos(x-z-1.41)-13.2*cos(x-y-1.38)=0
3.42-36*cos(y-z-1.38)-48.8*cos(y-x-1.38)=0
34.1-76.5*cos(z-y-1.38)-83.4*cos(z-x-1.41)=0
I tried fsolve and feval functions but i did not get any answer!!
thanks in advance for help
  2 个评论
Walter Roberson
Walter Roberson 2015-8-5
No real-valued solutions. I did not check for complex solutions.

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回答（1 个）

Matt J
Matt J 2015-8-5
The code below does a search for the minimum by numerical sampling of x,y,z at 1 degree intervals. It does not find a point that brings F close to zero, indicating that there probably is no solution,
[x,y,z]=ndgrid(single(linspace(-pi,pi,360)));
F1=-1.63-10.6*cos(x-z-1.41)-13.2*cos(x-y-1.38);
F2=3.42-36*cos(y-z-1.38)-48.8*cos(y-x-1.38);
F3=34.1-76.5*cos(z-y-1.38)-83.4*cos(z-x-1.41);
F=abs(F1)+abs(F2)+abs(F3);
[minval,i]=min(F(:));
xyz_min=[x(i),y(i),z(i)],
minval,
  1 个评论
Hazem
Hazem 2015-8-6
by using this code .... i am getting minimum value of the function F around(6.18)
by using fval function i got 0.233, but still it does not reach to zero
any way ... from your answer and from Mr.Walter's answer i can be sure that this set of non linear equations is unsolvable (or at least no real solution)
thanks for your help ... i really appreciate that

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