%TWOBVP Solve a BVP that has exactly two solutions.
% TWOBVP uses BVP4C to compute the two solutions of
% y'' + |y| = 0
% that satisfy the boundary conditions
% y(0) = 0, y(4) = -2
% This example illustrates how different initial guesses can lead to
% different solutions.
%
% See also: TWOODE, TWOBC, BVPINIT, BVP4C, BVPVAL, BVPGET, BVPSET, @.
% Jacek Kierzenka and Lawrence F. Shampine
% Copyright 1984-2000 The MathWorks, Inc.
% $Revision: 1.4 $ $Date: 2000/08/30 20:52:08 $
% One solution is obtained using an initial guess of y1(x)=1, y2(x)=0
solinit = bvpinit(linspace(0,4,5),[1 0]);
sol = bvp4c(@twoode,@twobc,solinit);
x = linspace(0,4);
y1 = bvpval(sol,x);
figure;
%plot(x,y1(1,:));
plot(x,y1(1,:),'-k');
xlabel('x');
ylabel('y');
% The other solution is obtained using an initial guess of y1(x)=-1, y2(x)=0
solinit = bvpinit(linspace(0,4,5),[-1 0]);
sol = bvp4c(@twoode,@twobc,solinit);
y2 = bvpval(sol,x);
% Plot both solutions
figure;
%plot(x,y1(1,:),x,y2(1,:));
plot(x,y1(1,:),'-k',x,y2(1,:),'--k');
xlabel('x');
%ylabel('solution y');
ylabel('y');
%title('A BVP with two solutions');
title('');
