How to implement mesh diagram?

How to do the mesh diagram in this coding with the corresponding of T,L and time?

Below here are my codes:

clc;
clear all;
L=20; 
alpha=0.23; 
t_final=60; 
n=20; 
T0=20; 
T1s=100; 
T2s=0; 
dx=L/n;
dt=2;
x=dx/2:dx:L-dx/2;
T=ones(n,1)*T0;
dTdt=zeros(n,1);
t=0:dt:t_final;
for j=1:length(t)
    for i=2:n-1
        dTdt(i)=alpha*(T(i+1)+T(i-1)-2*T(i))/dx^2;
    end
    dTdt(1)=alpha*(T(2)+T1s-2*T(1))/dx^2;
    dTdt(n)=alpha*(T2s+T(n-1)-2*T(n))/dx^2;
    T=T+dTdt*dt;
end
    disp(T)
    figure(1)
    plot(x,T,'Linewidth',3)
    axis([0 L 0 50])
    xlabel('Distance(m)')
    ylabel('Temperature(\circC)')

Answer 1

[Walter Roberson]

L=20; 
alpha=0.23; 
t_final=60; 
n=20; 
T0=20; 
T1s=100; 
T2s=0; 
dx=L/n;
dt=2;
x=dx/2:dx:L-dx/2;

t = 0:dt:t_final;
nt = length(t);
T = zeros(n, nt);
T(:,1) = T0;


for j=1:nt-1
    dTdt=zeros(n,1);
    for i=2:n-1
        dTdt(i) = alpha*(T(i+1,j)+T(i-1,j)-2*T(i,j))/dx^2;
    end
    dTdt(1) = alpha*(T(2,j)+T1s-2*T(1,j))/dx^2;
    dTdt(n) = alpha*(T2s+T(n-1,j)-2*T(n,j))/dx^2;
    T(:,j+1) = T(:,j) + dTdt*dt;
end

disp(T)

  Columns 1 through 17

   20.0000   56.8000   59.7440   67.7664   69.6541   73.2500   74.6082   76.6726   77.7084   79.0632   79.8832   80.8515   81.5184   82.2527   82.8066   83.3881   83.8561
   20.0000   20.0000   36.9280   39.6365   47.1254   49.4526   53.7042   55.5970   58.3620   59.9089   61.8713   63.1527   64.6331   65.7095   66.8773   67.7936   68.7463
   20.0000   20.0000   20.0000   27.7869   29.6557   34.8979   36.9150   40.5322   42.3785   45.0208   46.6451   48.6722   50.0879   51.7051   52.9399   54.2702   55.3525
   20.0000   20.0000   20.0000   20.0000   23.5820   24.7282   27.9892   29.4811   32.1391   33.6637   35.8257   37.2693   39.0583   40.3851   41.8945   43.0996   44.3958
   20.0000   20.0000   20.0000   20.0000   20.0000   21.6477   22.3068   24.2082   25.2140   27.0066   28.1446   29.7555   30.9131   32.3464   33.4688   34.7467   35.8096
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.7579   21.1218   22.1859   22.8235   23.9654   24.7582   25.8837   26.7478   27.8212   28.7044   29.7143
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.3487   20.5439   21.1228   21.5096   22.2077   22.7327   23.4828   24.0936   24.8575   25.5144
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.1604   20.2630   20.5715   20.7985   21.2122   21.5457   22.0267   22.4386   22.9586
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0738   20.1269   20.2886   20.4167   20.6542   20.8551   21.1502   21.4118
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0339   20.0572   20.1375   20.1995   20.3251   20.4304   20.5951
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   19.9915   20.0003   19.9931   20.0179   20.0241   20.0686   20.0961
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   19.9816   19.9683   19.9278   19.9026   19.8496   19.8199   19.7665   19.7401
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   19.9599   19.9342   19.8571   19.8004   19.6969   19.6167   19.4997   19.4070   19.2879
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   19.9128   19.8640   19.7193   19.6226   19.4481   19.3168   19.1293   18.9780   18.7886   18.6296
   20.0000   20.0000   20.0000   20.0000   20.0000   20.0000   19.8105   19.7196   19.4535   19.2941   19.0086   18.8105   18.5291   18.3131   18.0447   17.8245   17.5729
   20.0000   20.0000   20.0000   20.0000   20.0000   19.5881   19.4233   18.9479   18.6965   18.2483   17.9638   17.5611   17.2717   16.9134   16.6328   16.3133   16.0479
   20.0000   20.0000   20.0000   20.0000   19.1045   18.8180   18.0027   17.6297   16.9652   16.5841   16.0436   15.6827   15.2354   14.9037   14.5264   14.2251   13.9011
   20.0000   20.0000   20.0000   18.0533   17.5861   16.2755   15.7713   14.8670   14.4054   13.7448   13.3387   12.8319   12.4780   12.0737   11.7650   11.4324   11.1619
   20.0000   20.0000   15.7680   15.0909   13.2186   12.6369   11.5739   11.1008   10.4095   10.0228    9.5322    9.2118    8.8417    8.5726    8.2807    8.0516    7.8134
   20.0000   10.8000   10.0640    8.0584    7.5865    6.6875    6.3480    5.8318    5.5729    5.2342    5.0292    4.7871    4.6204    4.4368    4.2983    4.1530    4.0360

  Columns 18 through 31

   84.3318   84.7329   85.1320   85.4801   85.8214   86.1267   86.4234   86.6937   86.9548   87.1960   87.4283   87.6451   87.8535   88.0495
   69.5357   70.3333   71.0207   71.7022   72.3066   72.8984   73.4344   73.9551   74.4340   74.8970   75.3278   75.7432   76.1331   76.5085
   56.4736   57.4279   58.3910   59.2382   60.0784   60.8352   61.5773   62.2576   62.9197   63.5346   64.1304   64.6890   65.2289   65.7387
   45.4862   46.6162   47.6030   48.6006   49.4954   50.3852   51.1991   51.9996   52.7422   53.4674   54.1473   54.8084   55.4329   56.0384
   36.9554   37.9497   38.9837   39.9083   40.8469   41.7045   42.5610   43.3559   44.1413   44.8782   45.6013   46.2853   46.9533   47.5891
   30.5862   31.5309   32.3744   33.2564   34.0627   34.8858   35.6509   36.4195   37.1425   37.8608   38.5423   39.2143   39.8559   40.4855
   26.2707   26.9457   27.6825   28.3572   29.0679   29.7305   30.4117   31.0549   31.7053   32.3248   32.9443   33.5381   34.1272   34.6944
   23.4227   23.9623   24.4574   25.0030   25.5135   26.0561   26.5706   27.1042   27.6149   28.1356   28.6372   29.1425   29.6316   30.1202
   21.7477   22.0552   22.4184   22.7586   23.1386   23.5003   23.8894   24.2638   24.6564   25.0368   25.4286   25.8102   26.1981   26.5773
   20.7412   20.9377   21.1189   21.3403   21.5499   21.7905   22.0221   22.2768   22.5249   22.7897   23.0495   23.3212   23.5889   23.8646
   20.1619   20.2140   20.3008   20.3777   20.4842   20.5842   20.7085   20.8291   20.9691   21.1074   21.2610   21.4141   21.5791   21.7444
   19.6958   19.6790   19.6499   19.6465   19.6360   19.6482   19.6571   19.6858   19.7140   19.7589   19.8052   19.8657   19.9287   20.0034
   19.1931   19.0808   18.9917   18.8924   18.8144   18.7316   18.6680   18.6037   18.5565   18.5111   18.4809   18.4542   18.4408   18.4321
   18.4463   18.2890   18.1175   17.9686   17.8128   17.6769   17.5391   17.4189   17.3004   17.1976   17.0986   17.0136   16.9340   16.8668
   17.3575   17.1244   16.9196   16.7061   16.5157   16.3227   16.1489   15.9765   15.8208   15.6689   15.5316   15.3999   15.2812   15.1689
   15.7618   15.5145   15.2577   15.0297   14.7990   14.5908   14.3840   14.1955   14.0110   13.8419   13.6783   13.5281   13.3843   13.2522
   13.6286   13.3463   13.1002   12.8516   12.6296   12.4093   12.2093   12.0133   11.8336   11.6593   11.4984   11.3436   11.2004   11.0636
   10.8816   10.6431   10.4024   10.1909    9.9813    9.7930    9.6086    9.4404    9.2772    9.1269    8.9820    8.8477    8.7191    8.5995
    7.6161    7.4167    7.2449    7.0745    6.9236    6.7758    6.6423    6.5127    6.3940    6.2796    6.1738    6.0722    5.9778    5.8877
    3.9171    3.8168    3.7170    3.6300    3.5447    3.4684    3.3944    3.3270    3.2620    3.2022    3.1448    3.0915    3.0405    2.9930

figure(1)
mesh(x,t,T.')
xlabel('Distance(m)')
ylabel('Temperature(\circC)')
zlabel('T, whatever that is')

[Deck Zhan Sim]

Thank you