Solving a linear equation using for loop and equationsToMatrix

Hi

I am trying to solve a linear equation whose number of variables are defined by the user

I do not know how to define a matrix for equations

(I know how to solve this with another method but I am trying to use equationsToMatrix)

Is my approach to define a matrix like eq(n) correct?

clc
clear all

%This program will solve 1D Heat Transfer through a wire

T_A=10; %input('please specify the temperature at left \n')  %Bounndary condition
T_B= 40; %input('please specify the temperature at Right \n')  %Boundary condition
k= 100; %input('please specify the Conductivity \n')
node=input('please specify the number of nodes \n')
L=5 %input('please specify the Length  of the wire \n')
S=100; %input('Heat generation rate in the wire \n')

syms T [1 node];
d=L/node;
D=k/d;
A=0.1;
V=A*d;

for n= 1:node
    switch n
    case n==1
        
        a_L=0;
        a_R=D.*A;
        S_p=-2.*D.*A;
        S_u=T_A.*(2.*D.*A+(S.*V));
        a_p=a_L+a_R-S_p;
        
        eq(n)= (a_p.*T(n))-(a_L.*T_B)-(a_R.*T(n+1))==S_u;
        
        case n==node
             a_R=0;
             a_L=D.*A;
             S_p=-2.*D.*A;
             S_u=T_B.*(2.*D.*A+(S.*V));
             a_p=a_R+a_L-S_p;

        
        eq(n)= (a_p.*T(n))-(a_R.*T_A)-(a_L.*T(n-1))==s_u;
        
        otherwise
            S_p=0;
            S_u=S.*V;
            a_R=A.*D;
            a_L=A.*D;
            a_p=a_L+a_R-S_p;
            eq(n)= (T(n).*a_p)-((T(n-1)).*a_L)-((T(n+1)).*a_R)==S_u;
            
    end
end
[Z,Y] = equationsToMatrix(eq , T)

[Torsten]

What error message do you get ?

[Mohammad Assar]

The error was "Index exceeds the number of array elements" at line 47 (the last equation that I defined after "otherwise")