Not enough input arguments
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function xdot = OD(t,x)
global A B C Da K
Aa=A+(B*K*C);
Ba=B*Da;
u=K*x;
xdot=(Aa*x)+(Ba*u);
end
When running this code it show error in the line u=K*x; as not enough inputs. Here A,B,C,Da,K are all 2x2 matrix.
8 个评论
Vashist Hegde
2020-6-30
The code looks fine. The error does not seem to be for line:5
Are you sure that while running this function, you are giving t,x as arguments?
Sargondjani
2020-6-30
Look at the workspace when you get the error (with "dbstop if error"). Are K and x defined?
Rik
2020-6-30
Did you run this function with the green button (or with the f5 hotkey)?
Reeshabh Kumar Ranjan
2020-6-30
Did you save the file before running it again?
Stephen23
2020-7-1
Rather than using global variables you should parameterize the function:
Gopika R
2020-7-1
Gopika R
2020-7-1
Walter Roberson
2020-7-1
When you use the green run button, then where are you expecting that MATLAB will look for the values of t and x to use inside the routine?
采纳的回答
Ameer Hamza
2020-7-1
It seems that you are trying to solve a matrix differential equation. If you are using ode45, one possible way this error can occur if you call it like this
ode45(@(t,x) OD, [0 10], [1; -1; 0; 0])
The correct syntax is
ode45(@(t,x) OD(t,x), [0 10], [1; -1; 0; 0]) % or
ode45(@OD, [0 10], [1; -1; 0; 0])
The following shows working code with random values for matrices
global A B C Da K
A = rand(4);
B = rand(4);
C = rand(4);
Da = rand(4);
K = rand(4);
ode45(@(t,x) OD, [0 10], [1; -1; 0; 0])
function xdot = OD(t,x)
global A B C Da K
Aa=A+(B*K*C);
Ba=B*Da;
u=K*x;
xdot=(Aa*x)+(Ba*u);
end
Also, using global variables is not a good coding practice. Following shows how to pass these matrices to function OD without using global
A = rand(4);
B = rand(4);
C = rand(4);
Da = rand(4);
K = rand(4);
ode45(@(t,x) OD(t,x,A,B,C,Da,K), [0 10], [1; -1; 0; 0])
function xdot = OD(t,x,A,B,C,Da,K)
Aa=A+(B*K*C);
Ba=B*Da;
u=K*x;
xdot=(Aa*x)+(Ba*u);
end
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