function z=BVPSample(s)
% This function creates the error for a boundary value problem:
%  y''=4y,  y(0)=1 and we want y(1)=3.  The input s is the initial
%  velocity.

[t,y]=ode45(@BVPeqn,[0,1],[1;s]);
z=y(end,1)-3;