Hi,
The solution returned by fsolve seems to be a valid one because: -->Q([1.496447;0.9574371 ],0) ans = - 0.0000002 - 0.0000001 You say that the initial guess of [1.5;-0.9] is close to the expected values, however: -->Q([1.5;-0.9],0) ans = - 7.54 - 0.077934 is far from being zero. So there is probably a typo in your equations. PS: Another trivial solution is: -->Q([-0.9574371,-1.496447],0) ans = - 0.0000002 - 0.0000001 Such non-linear problems should have multiple solutions, including complex ones. Regards, Rafael -----Original Message----- From: users [mailto:[email protected]] On Behalf Of Hermes Sent: Sunday, September 17, 2017 8:25 AM To: [email protected] Subject: Re: [Scilab-users] solve a system of equations in scilab Hello, Please I need your comments. I have tried to solve the system with different initial conditions for fsolve and I always get the same wrong result for the second variable. function Sys=Q(x,z) Sys(1)=(x(1)-2)^2+(x(2)+2)^2+z^2-9; Sys(2)=x(1)^6+x(2)^6+z^6-12; endfunction z=0; [j,v,info]=fsolve([*1.5;-0.9*],list(Q,z)) disp(j,v,info) Even when putting these initial values, very similar to the expected values, fsolve returns 1.496447 0.9574371 the second positive value By using these values as initial values in this script: //Draghilev's Method clear; function Sys=Q(x,z) Sys(1)=(x(1)-2)^2+(x(2)+2)^2+z^2-9; Sys(2)=x(1)^6+x(2)^6+z^6-12; endfunction z=0; [j,v,info]=fsolve([1.5;-0.9],list(Q,z)) disp(j,v,info) N=100; smin=0.0; smax=0.046; h=0.001; x01=1.496447; //3.9691163496*10^-12; x02=0.9574371; //0.353580783; x03=0; //-1.5130442808; ics=[x01; x02; x03]; disp(["x(3)^2+(x(2)-2)^2+(x(1)-2)^2-9";"x(3)^6+x(2)^6+x(1)^6-12"],"systema") disp(["2*(x(1)-2),2*(x(2)-2),2*x(3)";"6*x(1)^5,6*x(2)^5,6*x(3)^5"],"jacobian(Vm,[x(1),x(2),x(3)])"); // //D1=12*x(2)^5*x(3)-12*(x(2)-2)*x(3)^5; //D2=12*(x(1)-2)*x(3)^5-12*x(1)^5*x(3); //DD=12*x(1)^5*(x(2)-2)-12*(x(1)-2)*x(2)^5; function dydt=odes(t,x) //dydt=zeros(x); dydt(1)=-12*x(2)^5*x(3)-12*(x(2)-2)*x(3)^5; dydt(2)=12*(x(1)-2)*x(3)^5-12*x(1)^5*x(3); dydt(3)=12*x(1)^5*(x(2)-2)-12*(x(1)-2)*x(2)^5; endfunction step=smax/N; t=[smin:step:smax*N]; t0=0 atol=h/100000; rtol=h/100000; LL= ode("rk", ics,t0, t',atol,rtol,odes) LL=LL' a=gca();//get the handle of the newly created axes param3d1(LL(:,3),LL(:,2),LL(:,1),alpha=35,theta=45,"X@Y@Z",flag=[2,2]) a.rotation_angles=[65,75]; The calculations have taken a long time without converging to the solution. I have interrupted the execution of the same. By entering the correct values, almost instantaneously, you get the soclucion of the system. Help Me!!! gracias -- Sent from: http://mailinglists.scilab.org/Scilab-users-Mailing-Lists-Archives-f2602246.html _______________________________________________ users mailing list [email protected]<mailto:[email protected]> http://lists.scilab.org/mailman/listinfo/users
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