RBasis3GaussianG.asv

function V=RBasis3GaussianAmerican(theta,~)

% Theta Methods(without matrix iniversion) for solving the ODE's

%clear all
format('longE')
global c

t=cputime;

r=0.1;sigma=0.20;T=1.;

S_min=0;S_max=2;

E=1;epsilon=0.01;C=r*E;theta=0.0;

N=21;

h=(S_max-S_min)/(N-1);

%c=1.5*h;
c=2.1*h;

Y=linspace(S_min,S_max,N);

M=100;

k=T/M;

% ****************************************************

% Matrix P

L=L1(Y); L_Sy=L1_Sy(Y); L_Syy=L1_Syy(Y);

CND=cond(L)

P=(1/2)*sigma^2*(L_Syy)+r*(L_Sy)-r*L;

LL=L-(1-theta)*k*P;

PP=L+theta*k*P;

[LL1,UU1]=lu(LL);

[LL2,UU2]=lu(L);

% ******************************************

% Initial Condition

U0=ic(Y);

a=UU2\(LL2\U0);

% ***********************************************

iplot=1;

for i=1:M

    b=PP*a;

    for j=1:N

        Q(j)=epsilon*C/(L(j,:)*a+epsilon-(E-Y(j)));

    end

    an=UU1\(LL1\(b+k*Q'));

    Un=L*an;

    Un(1)=E;

    Un(N)=0;

    a=UU2\(LL2\Un);

%     if mod(i,10)==1
% 
%         for j=1:N
% 
%             W(iplot,j)=U(Y(j),a,Y);
% 
%         end
% 
%         iplot = iplot+1;
% 
%     end

end

% surf(W);

colormap(hot);

SS=[0.6:0.1:1.4]
FD1001=[0.4000037 0.3001161 0.2020397 0.1169591 0.0602833 0.0293272 ...
    0.0140864 0.0070408 0.0038609];
for i=1:(length(SS))

   V(i)=U(SS(i),a,Y);

end;

temp=0;

for i=1:length(SS)

   temp=temp+(max(E-SS(i),0)-V(i))^2;
k(i)=max(E-SS(i),0);
end;

RMSE=sqrt(temp/length(SS))
error2=norm(FD1001-V)/(length(SS))
time=cputime-t

h=plot(SS,V,'--rs',SS,k);
xlabel('ASSET PRICE')
ylabel('VALUE OF OPTION')
legend('option price','payoff')
set(h,'LineWidth',2)
%title('Graph of Gaussian-RBF at 101 Nodes')
% ****************************************************

function y=U(x,a,Y)

N=length(Y);

y=0;

for i=1:N

   y=y+a(i)*phi(x,Y(i));

end;



% *********************************************************   



function y=phi(x,yj)

global c

%c=0.05;

  %y=sqrt((x-yj)^2+c^2);

  y=exp(-(x-yj)^2/c^2);
%y=(c^2 +(x-yj)^2)^(-1/2);
  

% ****************************************************

  

function y=phi_y(x,yj)

global c

%c=0.05;

  %y=(x-yj)/(sqrt((x-yj)^2+c^2));

  y=(-2*(x-yj)/c^2)*exp(-(x-yj)^2/c^2);
%y=(x-yj)/(c^2 +(x-yj)^2)^(3/2);


% ****************************************************



function y= phi_yy(x,yj)

global c

%c=0.05;

%y=1/sqrt((x-yj)^2+c^2)- ((x-yj)^2)/(((x-yj)^2+c^2)^(3/2));

   y=-2/c^2*exp(-(x-yj)^2/c^2)+4*(x-yj)^2/c^4*exp(-(x-yj)^2/c^2); 

 %y=-(-2*x^2 +4*x*yj-2*yj^2 +c^2)/(c^2 +(x-yj)^2)^(5/2);

% **********************************************************



function y=L1(Y)

N=length(Y);

for i=1:N 

   for j=1:N

      y(i,j)=phi(Y(i),Y(j));

   end

end



% *************************************************************



function y=L1_Sy(Y)

N=length(Y);

for i=1:N 

   for j=1:N

      y(i,j)=Y(i)*phi_y(Y(i),Y(j));

   end

end



% ******************************************************



function y=L1_Syy(Y)

N=length(Y);

for i=1:N 

   for j=1:N

      y(i,j)=Y(i)*phi_yy(Y(i),Y(j));

   end

end



% ***********************************************************



function y=ic(Y)

E=1;

N=length(Y);

y=zeros(N,1);

for i=1:N

   y(i)=max(E-Y(i),0);

end



% *************************************************************