function bacteriaODE(x0,T,lalambda,s)

% solves the initial value problem x'= lambda x, x(0)=x0
% by Runge-Kutta-Fehlberg (explicit) or by the trapezoidal rule (implicit)
% parameter:
% initial value x0; final time T; lambda, 
% method selection explicit (s=0) or implicit (s=1)
% examples: dahlquistODE(1,1,-10,s) versus  dahlquistODE(1,1,-100000,s) for s=0,1

global lambda;

lambda = lalambda;

if nargin==3 s=0; end

if s 
ode23t('dahlquist',[0 T],x0,odeset('OutputFcn',@odeplot))
else 
ode45('dahlquist',[0 T],x0,odeset('OutputFcn',@odeplot))
end

clear

return