STuck at coding second order differential equation (mx"+cx'+kx=f0coswt)

Error at line 6. Could you help me, please.

function Xdot=num_for(t,X)
m=100; k=1000; c=160;
ze=c/(2*sqrt(k*m));
wn=sqrt(k/m);
w=5; F=160; f=F/m;
f=[0; f*cos(w*t)];
A=[0 1;-wn*wn -2*ze*wn];
Xdot=A*X+f;

Tspan=[0 10];
y0=[0.01;0.1];
[t,y]=ode45('num_for',Tspan,Y0);
plot(t,y(:,1))

Answer 1

[Star Strider]

Refer to the ‘num_for’ function as a function handle. Quoted character arays ar not longer recognised.

Tspan=[0 10];
y0=[0.01;0.1];
[t,y]=ode45(@num_for,Tspan,y0);

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

function Xdot=num_for(t,X)
m=100; k=1000; c=160;
ze=c/(2*sqrt(k*m));
wn=sqrt(k/m);
w=5; F=160; f=F/m;
f=[0; f*cos(w*t)];
A=[0 1;-wn*wn -2*ze*wn];
Xdot=A*X+f;
end

If you are unfamiliar with function handles, see What Is a Function Handle? for details.

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