h=0.1;		
t=-1:h:0;
m = length(t);
x(m)=0;
x(m-1)=-h+x1(m);
for i=1:m-2,	
   x(m-i-1)=2*x1(m-i)- x1(m-i+1) - x(m-i)*(1+(t(m-i))^2);
end
plot(t,x(:,1),'r');
h=0.1;		
t=0:h:1;
x(m)=0;
x(m-1)=-h+x1(m);
for i=2:length(t)-1,	
   x(i+1)=2*x(i)- x(i-1) - x(i)*(1+(t(i))^2);
end

hold on

plot(t,x(:,1),'r');
axis([-2,2,-1.5,1.5]);

h=0.02;		
t=0:h:1;	

clear x;	
x(1,:)=[0 -1];	
for i=2:length(t),	
   k1=[x(i-1,2) (-(1+(t(i)*t(i)))*x(i-1,1))];	
   x(i,:)=x(i-1,:)+k1*h;		
   
end

plot(t,x(:,1),'b');
axis([-2,2,-1.5,1.5]);


h=0.1;		
t=-1:h:0;

clear x;

x(1,:)=[0 -1];	
for i=2:length(t),	
   
   k1=[x(i-1,2) (-(1+(t(i)*t(i)))*x(i-1,1))];
   x(i,:)=x(i-1,:)+k1*h;	
   
end

hold on

plot(t,x(:,1),'r');
axis([-2,2,-1.5,1.5]);

h=0.02;		
t=-1:h:0;	

clear x;	
x(1,:)=[0 -1];	
for i=2:length(t),	
   k1=[x(i-1,2) (-(1+(t(i)*t(i)))*x(i-1,1))];	
   x(i,:)=x(i-1,:)+k1*h;		
   
end

plot(t,x(:,1),'b');
axis([-2,2,-1.5,1.5]);