Negative initial value problem. Index must be a positive integer or logical.

When I tried to run this code :

         yprime= @(t,y) (.01)*(6*(t^5)-10*(t^4)-104*(t^3)+84*(t^2)+290*t-26)

         y(-4)= 0.4

         t_range = [-4,5]

I get this error message: "Attempted to access y(-4); index must be a positive integer or logical."

Any ideas for how to fix this. I am just learning MatLab and I don't think we are expected to do anything too advanced.

Answer 1

[Star Strider]

Initial conditions have to start at t=0, understood by definition. You would have to define it a ‘y0 = 0.4’.

This works:

yprime= @(t,y) (.01)*(6*(t^5)-10*(t^4)-104*(t^3)+84*(t^2)+290*t-26);
y0= 0.4;
t_range = [-4,5];
[t,y] = ode45(yprime, t_range, y0);