Solving 2nd Order ODE: y'' + 2y' - y = e^{-x}, y(0) = y'(0) = 1

[squenshl]

Homework Statement

Consider the following second order ODE
$$ y'' + 2y' - y = e^{-x}, \quad y(0) = y'(0) = 1. $$ Convert this to a system of first order equations and use the pc33assisys MATLAB file to compute the solution for y(2).

Homework Equations

The Attempt at a Solution

The system of first order equations is
$$ u_1' = u_2 \\ u_2' = e^{-x}-2u_2+u_1 $$ with $$ u_1(0) = u_2(0) = 1. $$
The solution for y(2) is y(2) = 3.27 to 2 d.p. But my pc33assisys file doesn't give me this. All the relevant files are attached to run the program. Can someone help figure out what is wrong with my code.

Thanks.

 

[milesyoung]

There's a matrix indexing error in pc33assi3sys.m in the Adams-Moulton integration loop. Whoever wrote it also forgot to initialize f(1,:) for the first multi-step.

I've attached a corrected version.

 

[squenshl]

Cheers mate