Unrecognized function or variable 'X0'.
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when i run the command it says "Unrecognized function or variable 'X0'." I need help. Thank you
[X, FVAL]= FSOLVE(@mintafun,X0,options),
4 个评论
Dyuman Joshi
2023-5-26
You need to define x0 and options outside of the ODE function.
And the function is fsolve in lower case. Also, there are multiple typos in your code (bracket misplaced, multiplication or division sign missing, etc) check out for them.
Bismark
2023-5-26
Stephen23
2023-5-26
"x0 =[10, 4 6 , etc] in the code"
x0 is not the same as X0
Bismark
2023-5-26
采纳的回答
There are actually a lot of errors with your code. It might be worth taking a step back and thinking through your approach.
First, MATLAB is case-sensitive, which means FSOLVE and fsolve, X and x, etc are not equivalent statements.
Second, you have created a function that appears to be written upside down. It also appears to contain at the very bottom the inputs you are using to call the function in fsolve.
Third, you must be explicit in your use of mathematical operators to use. MATLAB does not assume anything. For example, sigma(X(14) should probably be sigma*(X(14)
Finally, check for typos. For example ((X13) should probably be (X(13)
As for the error you are seeing right now, it is likely because you are trying to call your function without defining the inputs. Here, for example, I haven't defined the variable X0 yet.
[X, FVAL]= FSOLVE(@mintafun,X0,options),
The correct syntax might look like this, at which point, you will start getting new errors due to the other issues I describe above.
x0 = [10; 6; 4; 3; 4; 3; 2; 3; 18; 7; 25; 10; 5; 5; 4; 11; 8; 20; 6; 3; 8; 1; 30; 7; 2; 6; 14; 30;];
options=optimset('Display','iter');
[X, FVAL]= fsolve(@mintafun,x0,options),
4 个评论
x0 = [0,0];
x = fsolve(@root2d,x0)
function F = root2d(x)
y = 0.5;
F(1) = exp(-exp(-(x(1)+x(2)))) - x(2)*(1+x(1)^2);
F(2) = x(1)*cos(x(2)) + x(2)*sin(x(1)) - y;
end
Bismark
2023-5-27
I refering to your defining equations that use variables that have not yet been defined. You can't use a variable (or array element, if that is your intent) if it hasn't yet been created.
Here's a shortened example
x0 = [10; 6; 4; 3; 4; 3; 2; 3; 18; 7; 25; 10; 5; 5; 4; 11; 8; 20; 6; 3; 8; 1; 30; 7; 2; 6; 14; 30];
F1 = mintafun(x0)
% The very first calculation uses phi, tau_c, theta, and tau_w, none of which exist yet.
function F = mintafun(X)
F =X(5)/X(12) - phi*(1 - tau_c)*X(1) / theta*(1 - tau_w)*(1-X(4));
tau_c = 0.17;
tau_w = 0.2;
theta = 0.349;
phi = 5;
end
Bismark
2023-5-29
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