From stuct to array

Hello everyone,

I have created a struct S as:

syms x1 x2 nnX1 nnX2
p1Space = linspace(0,50,10);
p2Space = linspace(0,25,10);

for i=1:10
    S(i) = vpasolve(x1^2 + x2^2 - p1Space(i) == 0, x1*x2 - p2Space(i) == 0, [x1 x2]);
end

and I get an error when I perfom the following for loop in order to store specific elements into two arrays (XX1 and XX2):

for k = 1:10
   XX1(k) = S(k).x1(2,1);
   XX2(k) = S(k).x2(2,l);
end

When I type in the command window for example S(4).x1(2,1), the number appears on the screen, but inside the for-loop, this doesn't work. Any ideas why is this happening and how can I store these spesific values into the XX1 and XX2 arrays?

Thank you

[Ameer Hamza]

You are getting this error because S(1).x1 does not have two elements. Similar is the case for S(1).x2. All the other elements of S have two elements, therefore S(4).x1(2,1) in the command window. Try S(1).x1(2,1) in the command window.

Answer 1

[Adam Danz]

As stated in the documentation, the size of the vpasolve output corresponds to the number of the solutions. On the first iteration, there is only 1 solution which can be seen here,

 S(1)
ans = 
  struct with fields:

    x1: [1×1 sym]
    x2: [1×1 sym]

On the first iteration of the k-loop (k=1), you're getting the error because you're trying to get the 2nd row of x1 and x2 but they only have 1 row.

Answer 2

[Konstantinos Andrikos]

Thank you for your responses. Problem solved!

[Adam Danz]

Glad I could help.