MA2051 - Ordinary Differential Equations
Matlab - Commands specific to MA 2051

Commands developed especially for MA 2051 include

dfield Direction field of first-order equation
weuler Numerical approxim ation to solution of initial-value problem via Euler method
wheun Like weuler but uses Heun method
wrk4 Like weuler but uses fourth-order Runge-Kutta

To learn how to use weuler, for example, type help weuler.

Each of these commands uses a so-called M-file to describe the differential equation in the form y' = f(t, y); e.g. , for the logistic equation tex2html_wrap_inli
ne352 ,P replaces y and tex2html_wrap_inline358 . The correspo nding M-file is

% logistic.m - logistic equation
% P' = a*P - s*P^2

function Pprime = logistic(t, P)   % Note lack of ; after function line
a = 0.0282;
s = 0.00021;
Pprime = a*P - s*P.^2;
Comments are preceded by %. Note that a and s have been given specific values so that this M-file can return the numerical value of the slope Pprime at any given values of t and P.

Next: Simple Plotting


© 1996 by Will Brother. All rights Reserved. File last modified on November 21, 1996.