Error using symsum and arrays for summing over array elements

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Tsz Tsun
Tsz Tsun 2024-4-6
评论： Tsz Tsun 2024-4-7
Ran in:
Hi all, I have a problem with using symsum and arrays. For example consider the following code, and I get the error 'Error using syms, using input and output arguments simultaneously is not supported '. How could I fix it?
array(1)=0.4;
array(2)=0.99;
array(3)=0.87;
array(4)=0.33;
array(5)=0.33;
array(6)=0.33;
array(7)=0.21;
array(8)=1.3;
array(9)=1.2;
array(10)=0.04;
disp(array)
0.4000 0.9900 0.8700 0.3300 0.3300 0.3300 0.2100 1.3000 1.2000 0.0400
syms q
trial = symsum( array(syms(q))*q^2 , q,2,7)
Error using syms (line 146)
Using input and output arguments simultaneously is not supported.

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采纳的回答

VBBV
VBBV 2024-4-6
编辑：VBBV 2024-4-6 
trial = symsum( array(double(q)).*q.^2 , q,2,7)
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VBBV
VBBV 2024-4-7
Ran in:
@Tsz Tsun you could also subs the symbolic variable for that index range and use sum
array(1)=0.4;
array(2)=0.99;
array(3)=0.87;
array(4)=0.33;
array(5)=0.33;
array(6)=0.33;
array(7)=0.21;
array(8)=1.3;
array(9)=1.2;
array(10)=0.04;
disp(array)
0.4000 0.9900 0.8700 0.3300 0.3300 0.3300 0.2100 1.3000 1.2000 0.0400
syms q
trial = sum(array(2:7).*subs(q.^2, q,2:7)) % subs the variable
trial = 
double(trial)
ans = 47.4900

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