Regarding the matrix indexing,

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surendra kumar Aralapura mariyappa 2019-7-19

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/472471-regarding-the-matrix-indexing

评论： surendra kumar Aralapura mariyappa 2019-7-19

采纳的回答： infinity

Hello all,

I have one problem in assigning index to the matrix.

I have two solver, one is mine and another is my professor.

This is mine:

function T = Euler_explicit(T_0, L, P,C, h,i)
A = inv(C)*L;           % Conductance and inverse of specific heat capacity
b = inv(C)*P;           % Power loss vector and inverse of specific heat capacity          
T = zeros(length(T_0),i);
T(:,1) = T_0;             % Initial condition T_0(:,1) = 273.50 Ambient temperature of environment   
   f_1 = f(A, b, T(:,i));            % Calling the differential equation function
   T(:, i+1) = T(:,i) + f_1*h;   %here I need to change the indexing, but I am not getting how to change it to get one row vector for each iteration _this is second question
end

Below is my professor: Kindly don't ask for the explantion to this solver, this is very complicated to explain here

function[T_akt] = solver_instationaer(T_akt,P,C,h,L)
% Konstante
b = 0.26;                                               % nach Carter S.3
% Berechnung mittels Näherungsverfahren Teil 1 nach Carter
a2 = (0.5-b)/b^2;                                       % nach Carter S. 3
a1 = 1/b-2*a2;                                          % nach Carter S. 3
a0 = 1-a1-a2;                                           % nach Carter S. 3
    % Berechnung mittels Näherungsverfahren nach Carter
%     C = zeros(n,n);                                       % zur Überprüfung der stationären Lösung
    X = (C+b*h*L)\(C*T_akt+b*h*P);                          % analog zu inv(C+b*h*G)*(C*T_vor+b*h*Q); nach Carter S. 3
    Y = (C+b*h*L)\(C*X+b*h*P);                              % analog zu inv(C+b*h*G)*(C*X+b*h*Q); nach Carter S. 3   
    T_akt = a0*T_akt+a1*X+a2*Y;                             % Berechnung des aktuellen Temperaturvektors nach Carter S. 3
end 

This is my main function file where I am calling two solver at two different time:

T_akt(1:n,1) = 273.50;   % n =  10 in this case
for t = 1:3600
    L = -(LA);
    for k = 1: n
        L(k,k) = -(sum(L(k,:)));
    end
    T_akt = solver_instationaer(T_akt,P,C,d_T,L);      %my professor
  % T_akt = Euler_explicit(T_akt, L, P,C, d_T,t);        %mine
   T1(:,t) = T_akt;
end

When I run the main function file with professor solver, it is giving one row vector T_akt in each iteration like below: for second iteration

When I run the main function file with my solver, it is giving the matrix like below: for second iteration, but It should give the new row vector only, not the vector of previous iteration

  %previous     % new
5615    273.5615
5015    273.5015
5000    273.5000
5000    273.5000
5000    273.5000
5000    273.5000
5000    273.5000
5000    273.5000
5000    273.5000
5000    273.5000

question: it gives the answer like above , But I need only one row vector, I mean vector of the respective iteration like my professor answer.

I thinl I need to make some changes in my slover index especially, here, But I need to know what those changes are.

T = zeros(length(T_0),i);
T(:,1) = T_0;             % Initial condition T_0(:,1) = 273.50 Ambient temperature of environment   
   f_1 = f(A, b, T(:,i));            % Calling the differential equation function
   T(:, i+1) = T(:,i) + f_1*h;   %here I need to change the indexing, but I am not getting how to change it to get one row vector for each iteration _this is second question
end

Kindly help me out in fixing this problem.

Don't Mind two questions at a time, one is simple but another I don't Know?

any suggestions and answers are most welcomed

Thanks in advance

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Guillaume 2019-7-19

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surendra kumar Aralapura mariyappa 2019-7-19

Thank you Guillaume.

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Answer 1

infinity 2019-7-19

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/472471-regarding-the-matrix-indexing#answer_383903

Hello,

How about if you modify your function like this

function T = Euler_explicit(T_0, L, P,C, h)
A = inv(C)*L;           % Conductance and inverse of specific heat capacity
b = inv(C)*P;           % Power loss vector and inverse of specific heat capacity          
   f_1 = f(A, b, T_0);            % Calling the differential equation function
   T = T_0 + f_1*h;   %here I need to change the indexing, but I am not getting how to change it to get one row vector for each iteration _this is second question
end