Index in position 2 exceed array bounds

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Here's my code and im tryna figure out why i always get "index in position 2 exceed arra bounds"
What do i have to change?
function [t, y] = Euler_implicite(fonction, J ,t0,y0, h,e, Nt)
y(1,:) = y0;
t=zeros(Nt);
t(1) = t0;
for i = 1:Nt
g= y(:,i+1)-y(:,i)- h*fonction;
t(i+1)=t(i)+h;
y = newton_systeme(g,J,SP, niteration, precision);
end
newton_systeme(g,J,y0,e,Nt);
end
  9 个评论

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回答(2 个)

Adam Danz
Adam Danz 2019-4-11
编辑:Adam Danz 2019-4-11
Just before the i-loop, you set y equal to 10.
%from your code...
y0 = 10;
y(1,:) = y0; % same as y = 10
Then on the first iteration of the i-loop, i=1 so when you execute this line
g= y(:,i+1)-y(:,i)- h*fonction;
% ----------
you're trying to access the second value of y but y only has 1 value (y=10)!
Even if that didn't cause an error this section below would (also) cause an error.
g= y(:,i+1)-y(:,i)- h*fonction;
% -----------
K>> h*fonction
Undefined operator '*' for input arguments of type 'cell'.
So there's at least a couple areas of your code you need to re-think. In other words, your errors are conceptual errors. Your code isn't written properly and that's something you'll need to work on in the context of your project.
I suggest going through your code line-by-line to confirm that it's doing what it's supposed to be doing.
  3 个评论
Adam Danz
Adam Danz 2019-4-11
We don't have enough information to fix it (or confirm that it's broken). It's just a bunch of letters to us.
Bob Thompson
Bob Thompson 2019-4-12
What you need to do to fix your code is to figure out how to get more than one element in y. As has been mentioned already the calculation of g is looking for two elements of y when only one exists. We are not particularly able to help you fix this particular problem because it is a very contextual solution, not something to do with the code. All we can tell you is that this is why the code isn't working.

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jahanzaib ahmad
jahanzaib ahmad 2019-4-11
there is nothing in y(:,i+1)
  2 个评论
jahanzaib ahmad
jahanzaib ahmad 2019-4-11
u want to minus before and after values but when u reach last value it gives error .
for for i = 1:Nt -1
the last value will not change .
Maureen Domtche
Maureen Domtche 2019-4-11
i tried it didn't work , i get the same erroe message

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