Plotting diffusion eq.

I'm stuck at plotting the solution to the diffusion equation. For the provided c and D, what would be optimal time and distance values?

x = 0:0.01:10^5;
t = [100 200 300];
c = 10^(-6); 
D = 10^(-9); 
figure(1)
x0 = [0 0 10^10];
u0 = [c 0 0];
plot(x0, u0)
hold on
for i = 1:3
    dn = 2*D*sqrt(t(i));
    e2 = erf( -x/dn );
    u(i,:) = c*(1 + e2);  
    plot(x,u(i,:))
end
grid on
ylabel('Concentration (C) (mols/metres^{3})')
xlabel('Distance (x) (metres)')
legend('t = 0',['t = ' num2str(t(1))],['t = ' num2str(t(2))], ...
       ['t = ' num2str(t(3))])

Answer 1

[Alan Stevens]

Your x values are far too large! Try

x = (0:0.01:1)*10^-7;   %%%%%%%%%%%%%%%%%%% 
t = [100 200 300];
c = 10^(-6); 
D = 10^(-9); 
% figure(1)
% x0 = [0 0 10^10];
% u0 = [c 0 0];

for i = 1:3
    dn = 2*D*sqrt(t(i));
    e2 = erf( -x/dn );
    u(i,:) = c*(1 + e2);  
    
end
plot(x,u)
grid on
ylabel('Concentration (C) (mols/metres^{3})')
xlabel('Distance (x) (metres)')
legend(['t = ' num2str(t(1))],['t = ' num2str(t(2))], ...
       ['t = ' num2str(t(3))])

to get