How to retrieve the successive values from the given code

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MINATI 2020-1-12

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https://ww2.mathworks.cn/matlabcentral/answers/499958-how-to-retrieve-the-successive-values-from-the-given-code

评论： MINATI 2020-1-12

syms k r a b

k=7;F = zeros(k,1);F(1)=0;F(2)=1;F(3)=a/2;

for r = 1:k

F(k+3)=(symsum((r+1)*F(r+1)*(k-r+1)*F(k-r+1),r,0,k) -symsum((k-r+1)*F(r)*(k-r+2)*F(k-r+2),r,0,k)...

-symsum((k-r+1)*G(r)*(k-r+2)*F(k-r+2),r,0,k)+(M+L)*(k+1)*F(k+1))/((1+b)*(k+1)*(k+2)*(k+3));

end

disp(F(1:7))

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Walter Roberson 2020-1-12

在 MATLAB Online 中打开

F = zeroes(k, 1,'sym');

But you need to rewrite the symsum. It is never possible to use a symbolic variable as a subscript. You should just calculate the expression in vectorized form and sum()

Even if using symbolic variables as an index were permitted, with each of your symsum going to k, you are trying to access up to F(k+q) in each symsum even though you have not defined past F(r+2)

MINATI 2020-1-12