dP/dt = (2-0.1t)P as code:
function dP = finc1(t, P)
dP = (2 - 0.1 * t) * P;
end
And the function to integrate it:
P0 = 1000;
t0 = 0;
tEnd = 5;
tspan = [t0, tEnd];
[t, P] = ode45(@func1, tspan, P0);
plot(t, P)
Provide the function to be integrated as function handle with a leading @..., not as string. The latter works for backward compatibility with R5.3, such the it is outdated for almost 20 years now.
