help needed on using "solve" for equation including element from array

Hello, I'm having problem when using "solve" function. For example,

clear a k x y;

a=[1, 2];

for k=1:1:2
    y=subs(abs(solve('x^2+a(k)^2-9')))
end

Matlab gave me

y =

   abs(a(2)^2-9)^(1/2)
   abs(a(2)^2-9)^(1/2)

instead of numerical results. Of course, the real problem I'm trying to solve is much more complicated, and the array "a" is calculated by another code and actually a more complicated matrix, so I cannot manually assign each a(k) for a numerical number. Could anybody help me on this? I tried to search for an answer here but failed. Many thanks for any help.

Answer 1

[Walter Roberson]

syms x;

a=[1, 2];

for k=1:length(a)
  y=abs(double(solve(x^2+a(k)^2-9)))
end

Alternately,

syms x A;
SolveX = matlabFunction(vectorize(abs(solve(x^2 + A^2 - 9, x))));

y = SolveX(a);

You might have problems with imaginary roots: if any a is greater than 3 then the roots become imaginary. If a is 3 exactly then there is a single root, 0: that could be a problem for vectorization.

[newbie]

thank you, thank you, thank you