ode45 or dsolve

whats wrong with my code.. its from a book but cant run

tspan=[0 4];
y0=[0.02;0];
[t,y]=ode45('unforced1',tspan,y0);
plot(t,y(:,1));
grid on
xlabel(‘time’)
ylabel(‘Displacement’)
title(‘Displacement Vs Time’)
hold on;
its function is function yp = unforced1(t,y)
yp = [y(2);(-((c/m)*y(2))-((k/m)*y(1)))];

[Torsten]

You must give numerical values to k,c an m if you use ode45.

[felik kamwera]

okay m=5,, k=1000,c=1000, can u help how the code should look like

[Chinmay Anand]

What are c and m defined in your function ? Have you assigned any values to them ?

[felik kamwera]

should i give them values in the function definition or call?

Answer 1

[madhan ravi]

tspan=[0 4];
y0=[0.02;0];
m=5;
k=1000;
c=1000;
[t,y]=ode45(@(t,y)unforced1(t,y,c,m,k),tspan,y0); % function call
plot(t,y(:,1));
grid on
xlabel('time')
ylabel('Displacement')
title('Displacement Vs Time')

%function definition
function yp = unforced1(t,y,c,m,k) % if your version is prior to 2016b save this in a separate file name unforced1.m
yp = [y(2);
    (-((c/m)*y(2))-((k/m)*y(1)))];
end

[felik kamwera]

thank u very much...i have seen where i was wrong..again thank u