I have come across a matlab code for solving the spruce budworm differential equation.But,I would like to solve the same differential equation for a range of parameters(r=0:5,q=0:10).I am having problems trying to define the array of matrices for each loop.Please look at the code below:(adsbygoogle = window.adsbygoogle || []).push({});

% This program solves the differential equation

% du/dt = f(t,u) = ru(1-u/q) + u^2/(1 + u^2)

function spruceco

tspan = [0; 100]; %This command defines the time interval of interest.

u0 = [.1];

for q=0:10%I would like to add these here and then pass the values of q,r to the function f%

for r=0:5

[t,u] = ode15s(@f,tspan,u0)

% This command tells MATLAB to use the differential equation solver called ode15s to numerically compute the solution of the differential equation defined by the function f, for time interval tspan, and initial condition u0. The right-hand side of the equation tells MATLAB to store this output in vectors t (for the time points) and u (for the population density).

figure;

drawnow

plot(t,u(:,1)); %This tells MATLAB to plot the solution.

hold on

end

% --------------------------------------------------------------------------

function dudt = f(t,u) %This commands defines the function du/dt = f(t,u).

q=10;r=2;%I would like to solve the differential equation for q=0:10,r=0:5;How?Procedure?

dudt = [r*u(1)*(1-u(1)/q) - u(1)^2/(1+u(1)^2)]; %This command inputs the left-hand side of the spruce budworm

%differential equtaion.

end

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Spruce budworm diff.eq,parameter variation using matlab functions

**Physics Forums | Science Articles, Homework Help, Discussion**