Help with plotting the figure

I've developed the matlab code for the attached problem (Explicit method). It'll be helpful if someone check my code and correct me if I'm wrong. Also I need help for plotting the figure using contour map in two dimensions. And Finally how to add the stability requirement in the code? Matlab Code:

clc clear close all format long g

%step sizes delx=0.5; X=50; %delta x dely=0.5; Y=20; %delta y delt=1/20; T=20; %delta t Dx=1.0; Dy=0.2; %diffusivity coeff. rx=Dx*delt/delx^2; ry=Dy*delt/dely^2; n=X/delx; m=Y/dely; s=T/delt;

%Initial values C=zeros(n+1,m+1,s+1); %Dimention of the answer matrix

for i=(n/2+1-1/(2*delx)):(n/2+1+1/(2*delx)) for j=(m/2+1-1/(2*dely)):(m/2+1+1/(2*dely)) C(i,j,1)=1000; %initial concentration of the contaminant. end end

%Calculating each row Analytically

for k=1:s for j=2:m for i=2:n C(i,j,k+1)=(1-2*rx-2*ry)*C(i,j,k)+rx*C(i+1,j,k)+rx*C(i-1,j,k)+... ry*C(i,j+1,k)+ry*C(i,j-1,k); end end end