Can you help me please !

I run code Matlab:

function yp=khidonghoc(t,y)

m = 10;

cd = 0.2;

g = 9.81;

w = m*g;

tspan=[0 5];

y0=[0;100;0;10];

yp = zeros(4,1);

yp(1)= y(2);

yp(2) = ((-cd/m)*y(2)*(y(2)^2+y(4)^2)^(0.5));

yp(3) = y(4);

yp(4) = ((-w/m)-(cd/m)*y(4)*(y(2)^2+y(4)^2)^(0.5));

[t,y]=ode45('khidonghoc',tspan,y0);

plot(t,y(:,1),y(:,3))

hold on;grid on;

xlabel('X-Displacement')

ylabel('Y-Displacement')

title('X vs Y Displacement')

end

Matlab error: "Not enough input arguments.

Error in khidonghoc (line 9)

yp(1)= y(2);"

Thanks you very much.

[Adam]

Pass in some arguments! How did you call the function? It expects two input arguments so if you don't pass them in it will give you that error.

[Johnny Vendetta]

thank you Adam

Answer 1

[Torsten]

function main
  tspan=[0 5];
  y0=[0;100;0;10];
  [t,y]=ode45(@khidonghoc,tspan,y0);
  plot(t,y(:,1),t,y(:,3))
  hold on;grid on;
  xlabel('X-Displacement')
  ylabel('Y-Displacement')
  title('X vs Y Displacement')
end

function yp=khidonghoc(t,y)
  m = 10;
  cd = 0.2;
  g = 9.81;
  w = m*g;
  yp = zeros(4,1);
  yp(1)= y(2);
  yp(2) = ((-cd/m)*y(2)*(y(2)^2+y(4)^2)^(0.5));
  yp(3) = y(4);
  yp(4) = ((-w/m)-(cd/m)*y(4)*(y(2)^2+y(4)^2)^(0.5));
end

[Johnny Vendetta]

Thank you so much, Torsten.