Solving a system of function handles with fsolve
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Lennart Vogt
el 23 de Oct. de 2018
Comentada: Stephan
el 24 de Oct. de 2018
I have a problem using fsolve in order to solve a system of equations.
a1 to a6 are anonymous functions which are supposed to be equal to 0. T is a vector with six unknown variables T1 to T6. Each anonymous function consists of a term with at least two of those variables.
So with 6 equations and 6 unknowns the solver should be able to solve the system of equations.
I am calling the function like this:
T0 = [0 0 0 0 0 0];
Temp = fsolve(CalcTemps,T0)
function fun = CalcTemps(T)
global a1 a2 a3 a4 a5 a6
fun(1) = a1;
fun(2) = a2;
fun(3) = a3;
fun(4) = a4;
fun(5) = a5;
fun(6) = a6;
end
In my understanding the code is not working as it is not possible to store function handles in fun. I also tried to create fun as a cell array so that the function handles can be stored but then I get an error as fun has to be a function handle and not a cell array.
So my question is: Is it possible to store multiple function handles (a1 to a6) in a single function handle (fun)?
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Stephan
el 24 de Oct. de 2018
Editada: Stephan
el 24 de Oct. de 2018
Hi,
use:
calc_temp
function calc__tenp
T = @(T1,T2,T3,T4,T5,T6) [T1 T2 T3 T4 T5 T6]; % unknown variable vector
T_Amb = 20;
a1 = @(T)5*T(2)-T(1); % anonymous functions
a2 = @(T)2*T(3)-4*T(2);
a3 = @(T)T(4)-T(3);
a4 = @(T)2*T(5)-3*T(4);
a5 = @(T)3*T(6)-4*T(5);
a6 = @(T)5*T_Amb-4*T(6);
T0 = [20 20 20 20 20 20]; % initial guess
Temp = fsolve(@CalcTemps,T0)
function fun = CalcTemps(T)
fun(1) = a1(T); % ERROR is produced in this line
fun(2) = a2(T);
fun(3) = a3(T);
fun(4) = a4(T);
fun(5) = a5(T);
fun(6) = a6(T);
end
end
Results:
Temp =
31.2500 6.2500 12.5000 12.5000 18.7500 25.0000
Best regards
Stephan
2 comentarios
Stephan
el 24 de Oct. de 2018
Please accept useful answers in order to help other people with similar Problems finding helpful Solutions in the future.
Más respuestas (1)
Matt J
el 23 de Oct. de 2018
You need to evaluate your function at T,
function fun = CalcTemps(T)
global a1 a2 a3 a4 a5 a6
fun(1) = a1(T);
fun(2) = a2(T);
fun(3) = a3(T);
fun(4) = a4(T);
fun(5) = a5(T);
fun(6) = a6(T);
end
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