How to fix: "Index exceeds matrix dimension"

Question

Sanzhar Januzakov 2018-2-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/383020-how-to-fix-index-exceeds-matrix-dimension

编辑： Shounak Shastri 2018-2-16

Please help, trying to run while loop but it says that "Index exceeds matrix dimension" in "while(H(i)>Ha)". Guess I have a problem with increment and the size of Hs. Thank you in advance.

% Input Data
As = 5;          % cross-sectional area of the spacecraft (m^2)
Ap = 150;        % parachute area (m^2)
Hs = 150;        % initial height (km)
U  = 0;          % initial velocity (m/s)
Hp = 3;          % parachute deployment height (km)
Ha = 100;        % height of the atmosphere above the earth (km) 
M  = 850;        % mass of the spacecraft (kg)
C  = 0.7;        % drag coefficient
Tstep = 0.1;     % time step (s)
% Increment initialisation
i=1; H(i)=Hs; v(i)=0; s(i)=0; t(i)=0;
    %freefall without atmosphere
    while(H(i)>Ha)
          FD=0;
          g(i) = (40*10^7)/(6371+H(i))^2;
          a(i) = g(i);                                         % As FD = 0 
          s(i+1)= U*Tstep + 0.5*a(i)*(Tstep^(2));
          v(i+1)= U + a(i)*Tstep; 
          i=i+1; continue
      end

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Answer 1

Shounak Shastri 2018-2-16

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https://ww2.mathworks.cn/matlabcentral/answers/383020-how-to-fix-index-exceeds-matrix-dimension#answer_305447

编辑：Shounak Shastri 2018-2-16

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You are not updating H(i+1) in your while loop.

"i=1; H(i)=Hs;"

This line creates an array named "H" of size [1, 1] which has one value "Hs". In your loop, you are not doing anything to the array which would increase the size of "H".

I don't know what you are trying to do with the code but I am guessing you might want to do

H(i+1) = H(i) - s(i)

This will increase the size of your array and the loop would run till H(i) > Hs.