i need to solve 7 nonlinear equations with 7 unknowns and error is occurring while compiling the codes
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Bindhu PR
el 7 de Abr. de 2020
Comentada: Walter Roberson
el 28 de Abr. de 2020
G = 600:100:1200;
x0 = [300;300;300;300;300;300;300];
options = optimset('Display','off');
X(i) = NaN(1,length(G));
for i = 600:length(G)
fsol = fsolve(@(x) solutionsproblem(x,G(i)),x0,options);
X(i) = fsol(1);
end
function F = solutionsproblem(x,G)
Tg1 = 300;
Tg2 = 301.5;
Ta = 305.8;
Tl = 302;
Tf = 302;
Tb = 302;
Th = 300;
F(1) = 0.0425*G + 1.41*10^(-8)*x(2)^(4) + 1.34*x(2) - 9.12*10^(-9)*x(1)^(4) + 341 - 2402.77*x(1) + 2400*Tg1;
F(2) = 0.0204*G - (3.48*10^(-8) + 4.35*10^(-10)*1)*x(2)^(4) + 1.41*10^(-8)*x(1)^(4) + 8.01*10^(-11)* x(4)^(4) + 2.43*10^(-8)*x(3)^(4) + 4.35*10^(-10)*1*x(5)^(4) + 0.55*x(3) + 1.34*x(1) - 2401.87*x(2) + 2400*Tg2;
F(3) = 0.124*G - 4.88*10^(-8)*x(3)^(4) + 2.44*10^(-8)*1*x(2)^(4) + 2.44*10^(-8)*1*x(5)^(4)- 50.938*x(3) + 11.502*x(6) + 1.836* x(2) + 37.60*Ta;
F(4) = 0.011*G - 8.70*10^(-8)*x(5)^(4) + 4.35*10^(-10)*x(3)^(4)+ 4.35*10^(-10)*x(2)^(4) + 0.83*x(6) + 0.112*x(3) + 0.112*x(2) - (1.055 + (112.7/1))*x(5) + (112.7/1)*Tf;
F(5) = 2.17*10^(-3)*G - 1.6*10^(-10)*x(4)^(4) + 8.01*10^(-11)*x(7)^(4) + 8.01*10^(-11)*x(2)^(4) - 69.07*x(4) + 3.77*10^(-4)*x(7) + 0.02*x(3) + 0.02*x(2) + 69*Tl;
F(6) = -52.068*x(6) + 0.412*x(3) + 0.368*x(4)+ 0.368*x(5) + 0.46*x(2) + 50.78*Tb;
F(7)= 3.77*10^(-4)*x(4) + 8.01*10^(-11)*x(4)^(4) + 0.092*x(5) - 1254.1*x(7) - 8.01*10^(-11)*x(7)^(4) + 1254*Th;
end
3 comentarios
David Goodmanson
el 8 de Abr. de 2020
Hi Bindhu,
you have not defined the argument of X. Ordinarily if you had, say, X(b) it would complain about the undefined variable b. Here, unless you have already defined i as something else, it is assuming i = sqrt(-1)
Respuesta aceptada
Bindhu PR
el 12 de Abr. de 2020
Editada: Ameer Hamza
el 12 de Abr. de 2020
3 comentarios
Walter Roberson
el 12 de Abr. de 2020
Editada: Walter Roberson
el 12 de Abr. de 2020
X = zeros(length(G), 7); %initialize with zeros
And in loop
X(i, :) = fsol;
Más respuestas (2)
Ameer Hamza
el 8 de Abr. de 2020
Editada: Ameer Hamza
el 12 de Abr. de 2020
It is a common practice to initialize arrays with zeros instead of nan. Correct two lines in your code
syms G;
G = 600:100:1200;
x0 = [300;300;300;300;300;300;300];
options = optimset('Display','off');
X = zeros(numel(G), numel(x0)); % use X, instead of X(i), initialize with zeros
for i = 1:length(G) % start the loop counter from 1
X(i,:) = fsolve(@(x) solutionsproblem(x,G(i)),x0,options);
end
disp(X);
function F = solutionsproblem(x,G)
Tg1 = 300;
Tg2 = 301.5;
Ta = 305.8;
Tl = 302;
Tf = 302;
Tb = 302;
Th = 300;
F(1) = 0.0425*G + 1.41*10^(-8)*x(2)^(4) + 1.34*x(2) - 9.12*10^(-9)*x(1)^(4) + 341 - 2402.77*x(1) + 2400*Tg1;
F(2) = 0.0204*G - (3.48*10^(-8) + 4.35*10^(-10)*1)*x(2)^(4) + 1.41*10^(-8)*x(1)^(4) + 8.01*10^(-11)* x(4)^(4) + 2.43*10^(-8)*x(3)^(4) + 4.35*10^(-10)*1*x(5)^(4) + 0.55*x(3) + 1.34*x(1) - 2401.87*x(2) + 2400*Tg2;
F(3) = 0.124*G - 4.88*10^(-8)*x(3)^(4) + 2.44*10^(-8)*1*x(2)^(4) + 2.44*10^(-8)*1*x(5)^(4)- 50.938*x(3) + 11.502*x(6) + 1.836* x(2) + 37.60*Ta;
F(4) = 0.011*G - 8.70*10^(-8)*x(5)^(4) + 4.35*10^(-10)*x(3)^(4)+ 4.35*10^(-10)*x(2)^(4) + 0.83*x(6) + 0.112*x(3) + 0.112*x(2) - (1.055 + (112.7/1))*x(5) + (112.7/1)*Tf;
F(5) = 2.17*10^(-3)*G - 1.6*10^(-10)*x(4)^(4) + 8.01*10^(-11)*x(7)^(4) + 8.01*10^(-11)*x(2)^(4) - 69.07*x(4) + 3.77*10^(-4)*x(7) + 0.02*x(3) + 0.02*x(2) + 69*Tl;
F(6) = -52.068*x(6) + 0.412*x(3) + 0.368*x(4)+ 0.368*x(5) + 0.46*x(2) + 50.78*Tb;
F(7)= 3.77*10^(-4)*x(4) + 8.01*10^(-11)*x(4)^(4) + 0.092*x(5) - 1254.1*x(7) - 8.01*10^(-11)*x(7)^(4) + 1254*Th;
end
11 comentarios
Bindhu PR
el 13 de Abr. de 2020
10 comentarios
Walter Roberson
el 28 de Abr. de 2020
If you want to print out the values of x(1) to x(7), why not just disp() the values? You have already shown that you know how to use disp(), so we do not understand why you are asking this question. It tends to suggest to us that you want something more complicated than just displaying x(1) to x(7).
I already showed you in https://www.mathworks.com/matlabcentral/answers/516059-i-need-to-solve-7-nonlinear-equations-with-7-unknowns-and-error-is-occurring-while-compiling-the-cod#comment_827486 how to store all of the values as you compute them, and put them into the various named variables; it would be trivial to add appropriate disp() to that. But you seemed to want something else other than what I suggested and did not reply to me, and you did not explain how what you wanted differed from what I suggested to you; it did not seem to be worth my time to keep asking you questions about what you really wanted.
You are getting 7 outputs for each of the 7 values of G. Give us an example of how you would like the output to look.
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