The interp1 use in the documentation section for time-dependent parameters refers to vector arguments with a dependent variable as a function of time. The interpolation would then return an interpolated value of the dependent variable at a specific time.
You need to pass ‘tv’ (or some other time vector with appropriate limits) to ‘fun’ as well in order to do the interpolation —
tspan = 1:5;
y0 = 0;
a = 1:5;
tv = 1:5;
[t,y] = ode45(@(t,y)fun(t,y,a,tv),tspan, y0);
figure
plot(t, y)
grid
xlabel('Time')
ylabel('Y')
function v = fun(t,y,a,tv)
a = interp1(tv,a,t);
v = 2*a.*t;
end
That produces a consistent result.
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