dirfield.m

matlab codes for solving ODEs, including euler method, RK methods etc, and some examples.

function dirfield(f,window,type)

t = linspace(window(1),window(2),21);
y = linspace(window(3),window(4),21);

[T,Y] = meshgrid(t,y);

S = feval(f,T,Y);

N = sqrt(1 + S.^2);
dT = 1./N;
dY = S./N;

switch type
    case 'arrow'; quiver(T,Y,dT,dY);
    case 'line'; quiver(T,Y,dT,dY,'.');
    otherwise; disp('type not implemented');
end

axis tight; grid on;