I need to send variables to solve(). How do I do it?

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Kushagra Vidyarthi 2015-2-27

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关闭： MATLAB Answer Bot 2021-8-20

Hello,

I have to send 3 variables to solve(). I have defined two of these variables such that their values are precomputed in a loop. The value changes every loop. So I need to define the as variables. I need to use the solve command to get the value of the third variable. But I cannot do that and the output is a symbol. I wrote the following loop to do this.

for i = 1:1:60

    syms lambda;
    a = (V(i)*cos(D(i)/W))/(omega*R);
    b = (V(i)*sin(D(i)/W))/(omega*R);
    temp = solve(Ct-(2*lambda*sqrt(a^2 + (b+lambda)^2))==0,lambda);
end

V,D are variables with a value changing every iteration of the loop (predefined). W, omega,Ct and R have constant values.

Help appreciated. Thanks

Kushagra

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Answer 1

Star Strider 2015-2-27

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编辑：Star Strider 2015-2-27

在 MATLAB Online 中打开

I would use fzero:

Ct = randi(100);                        % Pick A Number
R = randi(50);                          % Pick A Number
W = randi(10);                          % Pick A Number
omega = 2*pi*rand;                      % Pick A Number
V = randi(10, 1, 60);                   % Pick A Randonm Vector
D = 2*pi*rand(1,60);                    % Pick A Randonm Vector
for k1 = 1:length(V)
    a = (V(k1)*cos(D(k1)/W))/(omega*R);
    b = (V(k1)*sin(D(k1)/W))/(omega*R);
    fcn = @(lambda) Ct-(2*lambda*sqrt(a^2 + (b+lambda)^2));
    est_lambda(k1) = fzero(fcn, randi(10));
end

It’s best to not use ‘i’ and ‘j’ as variables, including as loop counters. MATLAB uses them for its imaginary operators, and using them otherwise can cause confusion.