symsum of matrix to extract element in the matrix
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i want to sum this:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/313535/image.png)
The code i used:
syms j
S=[0,1,0,0,0;1/2,0,1/2,0,0;0,1/2,0,1/2,0;0,0,1/2,0,1/2;0,0,0,1,0];
C1=symsum(S(1,j),j,1,5);
The code reterned me error. I want to do the polynomial summation as shwon above. l also would like to extract the element in matrix S for different j. Could you tell me what is the correct code i need to use? Thank you.
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回答(1 个)
Ameer Hamza
2020-6-10
Symbolic variables cannot be used as vector index. Also, your data is numeric, and it seems that you want to sum rows. Try this
S = [0,1,0,0,0;1/2,0,1/2,0,0;0,1/2,0,1/2,0;0,0,1/2,0,1/2;0,0,0,1,0];
C1 = sum(S, 2);
If you want to output in symbolic form
S = [0,1,0,0,0;1/2,0,1/2,0,0;0,1/2,0,1/2,0;0,0,1/2,0,1/2;0,0,0,1,0];
C1 = sum(sym(S), 2);
2 个评论
Ameer Hamza
2020-6-10
Try this
S = [0,1,0,0,0;1/2,0,1/2,0,0;0,1/2,0,1/2,0;0,0,1/2,0,1/2;0,0,0,1,0];
f = @(j) S(1, j);
Result
>> f(1) % j=1 => S11
ans =
0
>> f(2) % j=2 => S12
ans =
1
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