why do I receive ode15s error?

Here is my code:

clc

clear

close all

%Data

k = 247; % W/mK

rho = 2710; % kg/m^3

Cp = 900; % J/kgK

h = 120; % W/m^2K

D = 0.005; % m

To = 298.15; % K

T_infinity = 298.15; % K

Tb = 423.15; % K

Nx = 100; % Step

xo = 0; % m

xL = 0.1; % m

% Step and Increment

x = linspace(xo, xL, Nx);

dx = x(2) - x(1); % delta-x

t = linspace(0,3600,100); % time till 3600 s (1 hour)

% Simplify Calculation

a = k/(rho*Cp);

b = 4*h./(D*rho*Cp);

c = 2*dx*h./k;

% Initial Condition

IC = To.*ones(Nx,1);

% Solver ODE15s

[t,T] = ode15s (@f,t,IC,[],xo,xL,D,Tb,T_infinity,To,Nx,a,b,c,dx,x);

% Recalculation

T(:,1) = Tb; %BC1

T(:,end) = (c.*T_infinity + 4*T(:,end-1)-T(:,end-2))./(3+c); %BC2

% Visualization

imagesc(x,t,T)

colormap jet

colorbar

grid on

title ('Temperature Profile')

xlabel ('length of the fin')

ylabel ('Time in seconds')

% Function

function dTdt = f(t,T,xo,xL,D,Tb,T_infinity,To,Nx,a,b,c,dx,x)

dTdt = zeros(Nx,1);

T(1) = Tb; %BC1

T(end)= (c.*T_infinity + 4*T(end-1) - T(end-2))./(3+c); %BC2

% Interior

for i = 2 : Nx-1

d2Tdx2(i) = (T(i+1)- 2*T(i) + T(i-1))./dx.^2;

dTdt = (a.*d2Tdx2(i) - b.*(T(i)-T_infinity));

end

end

Answer 1

[Torsten]

clc
clear
close all

%Data
k = 247;                % W/mK
rho = 2710;             % kg/m^3
Cp = 900;               % J/kgK
h = 120;                % W/m^2K
D = 0.005;              % m
To = 298.15;            % K
T_infinity = 298.15;    % K
Tb = 423.15;            % K
Nx = 100;               % Step
xo = 0;                 % m
xL = 0.1;               % m

% Step and Increment
x = linspace(xo, xL, Nx);
dx = x(2) - x(1);           % delta-x
t = linspace(0,3600,100);   % time till 3600 s (1 hour)

% Simplify Calculation
a = k/(rho*Cp);
b = 4*h./(D*rho*Cp);
c = 2*dx*h./k;

% Initial Condition
IC = To.*ones(Nx,1);

% Solver ODE15s
[t,T] = ode15s (@(t,T)f(t,T,xo,xL,D,Tb,T_infinity,To,Nx,a,b,c,dx,x),t,IC);

% Recalculation
T(:,1) = Tb;                                                    %BC1
T(:,end) = (c.*T_infinity + 4*T(:,end-1)-T(:,end-2))./(3+c);    %BC2

% Visualization
imagesc(x,t,T)
colormap jet
colorbar
grid on
title ('Temperature Profile')
xlabel ('length of the fin')
ylabel ('Time in seconds')

% Function
function dTdt = f(t,T,xo,xL,D,Tb,T_infinity,To,Nx,a,b,c,dx,x)
dTdt = zeros(Nx,1);
T(1) = Tb;                                                      %BC1
T(end)= (c.*T_infinity + 4*T(end-1) - T(end-2))./(3+c);         %BC2

% Interior
for i = 2 : Nx-1
    d2Tdx2(i) = (T(i+1)- 2*T(i) + T(i-1))./dx.^2;
    dTdt(i) = (a.*d2Tdx2(i) - b.*(T(i)-T_infinity));
end
end  

[RR]

Thank you so much!