Problem in using symsum

I am writing a code to solve a problem by least square method. Can someone tell what is wrong in this code?

syms x k 
x(1)=-2;
x(2)=-1;
x(3)=0;
x(4)=1;
x(5)=2;
f(1)=-2;
f(2)=-1;
f(3)=0;
f(4)=1;
f(5)=2;
for i=0:4
    a(i)=symsum((x(k))^i,k,1,5)
end


Error using sym/subsindex (line 857)
Invalid indexing or function definition. Indexing must follow MATLAB indexing. Function arguments must be symbolic variables, and function body must be sym expression.

Error in sym/subsref (line 902)
            R_tilde = builtin('subsref',L_tilde,Idx);

Error in NMa2q2 (line 13)
    a(i)=symsum((x(k))^i,k,1,5)

Answer 1

[Bastian Arturo Romero Mardones]

syms x k 
x(1)=-2;
x(2)=-1;
x(3)=0;
x(4)=1;
x(5)=2;
f(1)=-2;
f(2)=-1;
f(3)=0;
f(4)=1;
f(5)=2;
for i=0:4 
    a{i+1}=symsum((x*(k)).^i,k,1,5) %change this line 
end

if you need double variables and not syms, use:

a{i+1}=double(symsum((x*(k)).^i,k,1,5))

[Ipshita]

After changing the line you specified, I am still not getting the answer. It is not able to take the values of x(1), x(2)... For a(1), I should get 0 for the given problem, but using your code, I am getting this:

a(1)

ans =

1×1 cell array

{1×5 sym}

[Bastian Arturo Romero Mardones]

But the symsum() function in your code returns 5 values, for each i value.

[Ipshita]

yes, it should return 5 values, i.e. a(1), a(2), a(3), a(4), a(5). But it is not returning, that is the problem.

[Bastian Arturo Romero Mardones]

did you try using double ()?

a{i+1}=double(symsum((x*(k)).^i,k,1,5)) 

with double() this is the output

maybe i don't understand good your problem, sorry