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Symsum and matrix usage error

1 次查看（过去 30 天）
Berke Ogulcan Parlak
关闭： MATLAB Answer Bot 2021-8-20
Screenshot_1.png
I need to write this algorithm, but I get an error like this:
Screenshot_2.png
This is my code:
A=[2,4,5;6,7,8;10,12,4];
n = length(A);
syms k
for i=1:n
for j=i+1:n
R(i,i)=sqrt(A(i,i)-symsum(R(k,i)^2,k,1,i-1));
R(i,j)=(A(i,j)-symsum(R(k,i)*R(k,j),k,1,i-1))/R(i,i);
end
end

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回答（1 个）

Walter Roberson
Walter Roberson 2019-11-5
It is never possible to use a symbolic variable as a subscript.
sum(u(1:i-1,i).*u(1:i-1,k))
If you need to generalize this to multiple i values then you should look at techniques such as using tril() and matrix multiplication.

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