Error "Not enough Input Arguments" in predator-prey model
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I'm trying to understand the working of ODE45 to solve multiple variable equations. I copied a code from internet but when I run this code, matlab gives error
Not enough input arguments.
Error in predPrey (line 2)
f=[-x(1)+3*x(3);-x(2)+2*x(3);x(1)^2-2*x(3)];
function f=predPrey(t,x);
the code is given here:
f=[-x(1)+3*x(3);-x(2)+2*x(3);x(1)^2-2*x(3)];
[t,xa] = ode45(@predPrey,[0 1.5],[0 1/2 3]);
plot(t,xa(:,2))
title('y(t)')
xlabel('t'), ylabel('y')
can someone please help me in this error so I can continue modifying model for my system.
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채택된 답변
Star Strider
2018년 1월 3일
You did not copy it correctly or implement it correctly.
Try this:
predPrey = @(t,x) [-x(1)+3*x(3);-x(2)+2*x(3);x(1)^2-2*x(3)];
[t,xa] = ode45(predPrey,[0 1.5],[0 1/2 3]);
plot(t,xa(:,2))
title('y(t)')
xlabel('t'), ylabel('y')
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추가 답변 (1개)
Walter Roberson
2018년 1월 3일
The way you give your code makes it appear as if all of your code is within predPrey.m and that your call to ode45 is on line 3 of predPrey.m and that you try to run the ode by executing the predPrey file. If so then you need to break out the line starting from [t,xa] into a different file. Or, if you are running R2016b or later, you could use one file that is not named prepPrey.m that contains
[t,xa] = ode45(@predPrey,[0 1.5],[0 1/2 3]);
plot(t,xa(:,2))
title('y(t)')
xlabel('t'), ylabel('y')
function f=predPrey(t,x)
f=[-x(1)+3*x(3);-x(2)+2*x(3);x(1)^2-2*x(3)];
The alternative to all of this is to use just one file containing:
prePrey = @(t, x) [-x(1)+3*x(3);-x(2)+2*x(3);x(1)^2-2*x(3)];
[t,xa] = ode45(predPrey,[0 1.5],[0 1/2 3]);
plot(t,xa(:,2))
title('y(t)')
xlabel('t'), ylabel('y')
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