Index exceeds the number of array elements. Index must not exceed 1

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sepideh
sepideh 2024-7-4
回答： Umar 2024-7-4
I dont understand why it stops after the first iteration and gives this error:
"Index exceeds the number of array elements. Index must not exceed 1"
g=9.8
nu= 10^-6 ;
c=1/2 ;
var_Y=0.1;
I_Y= 2.8;
s= 5;
C_beta=zeros(s)
C_Y=zeros(s)
S=0:1:4
for i=1:s
C_Y= (var_Y^2)*exp(abs(-S(i)./I_Y))
C_beta= (1/ (exp(c*var_y^2)))* ( ( exp(0.5*c*(c+1)*((var_y)^2) ) -1 )^2- c*(c+1) *(exp(0.5*c*(c+1)*(var_y)^2)-1)*(exp(var_y^2)-1)+(c^2)*(exp(C_Y(i))-1) )
plot (S,C_beta)
end

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采纳的回答

Aquatris
Aquatris 2024-7-4
编辑：Aquatris 2024-7-4
Ran in:
You are overwriting the C_Y array in your for loop. You initialize C_Y as a 5x5 zeros matrix and in the first iteration of your for loop, it becomes a 1x1 scalar.
g=9.8 ;
nu= 10^-6 ;
c=1/2 ;
var_Y=0.1;
I_Y= 2.8;
s= 5;
C_beta=zeros(1,s); % I think you want 1x5 not 5x5
C_Y=zeros(1,s) ; % THIS IS OVERWRITTEN IN YOUR FOR LOOP
S=0:1:4;
for i=1:s
C_Y(i)= (var_Y^2)*exp(abs(-S(i)./I_Y)); % SO CHANGE HERE TO STORE C_Y(i) instead of C_Y
C_beta(i)= (1/ (exp(c*var_Y^2)))* ((exp(0.5*c*(c+1)*((var_Y)^2))-1)^2- c*(c+1) *(exp(0.5*c*(c+1)*(var_Y)^2)-1)*(exp(var_Y^2)-1)+(c^2)*(exp(C_Y(i))-1) );
end
plot (S,C_beta);

更多回答（2 个）

Aditya
Aditya 2024-7-4
编辑：Aditya 2024-7-4
Hi Sepideh,
The error "Index exceeds the number of array elements. Index must not exceed 1" is likely due to an indexing issue in your loop. Specifically, the variable S is defined as a row vector with 5 elements, but you are trying to access S(i) where i ranges from 1 to s. However, your loop should iterate over the length of S instead of s.
Additionally, there are a few other issues in your code:
  1. C_Y and C_beta should be updated correctly inside the loop.
  2. var_y should be var_Y for consistency.
  3. The plot should be outside the loop to avoid overwriting it in each iteration.
Here is how you can update your code:
g = 9.8;
nu = 10^-6;
c = 1/2;
var_Y = 0.1;
I_Y = 2.8;
s = 5;
C_beta = zeros(1, s);
C_Y = zeros(1, s);
S = 0:1:4;
for i = 1:length(S)
C_Y(i) = (var_Y^2) * exp(abs(-S(i) / I_Y));
C_beta(i) = (1 / (exp(c * var_Y^2))) * ...
((exp(0.5 * c * (c + 1) * (var_Y^2)) - 1)^2 - ...
c * (c + 1) * (exp(0.5 * c * (c + 1) * (var_Y^2)) - 1) * ...
(exp(var_Y^2) - 1) + ...
(c^2) * (exp(C_Y(i)) - 1));
end
plot(S, C_beta);
I hope this resolves the issue that you are facing!
Umar
Umar 2024-7-4
Hi Sepideh,
After analyzing your code, it seems the variables C_Y and C_beta are being reassigned in each iteration without considering the previous values. This leads to incorrect indexing and array size mismatch errors.To resolve the issue and ensure proper calculation and plotting of C_beta, you need to modify the code to update specific elements of the arrays C_Y and C_beta in each iteration.
C_beta = zeros(s, 1); C_Y = zeros(s, 1);
Hopefully, making these modifications will help you achieve your desired goal.

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