Symbol to double error, 0x0 syms

am trying to solve a variable in an equation (syms x), I've simplified the equation. I am trying to store the value in P_9, a 1x1000 matrix by converting from a symbol to a double and am getting the error below. It is giving me a symbol of 0x0, which is where I think my error lies.

Please help me troubleshoot my code. Many thanks!

L
number = 1000;
P_9 = zeros(1,number);
A_t=0.67;
A_e = linspace(0,10,number);
for n=1:number
    %%find p9
    syms x
    eqn = x + 5 ==A_t/A_e(n);
    solx = solve(eqn,x);
    P_9(n) = double(solx);
end 

Warning: Explicit solution could not be found.

In solve at 179 In HW4 at 74 In an assignment A(I) = B, the number of elements in B and I must be the same.
Error in HW4 (line 76) P_9(n) = double(solx);

Answer 1

[Birdman]

You need to assign a numeric value when a solution is not found. Your array has to have a numeric value for each element of it in order to process. Therefore, your code can be modified as follows:

number = 1000;
P_9 = zeros(1,number);
A_t=0.67;
A_e = linspace(0,10,number);
for n=1:number
    %%find p9
    syms x
    eqn = x + 5 ==A_t/A_e(n);
    if isempty(double(solve(eqn,x)))
        P_9(n)=0;
    else
        P_9(n)=double(solve(eqn,x));
    end
end

[Walter Roberson]

number = 1000;
P_9 = zeros(1,number);
A_t=0.67;
A_e = linspace(0,10,number);
for n=1:number
    %%find p9
    syms x
    eqn = x + 5 ==A_t/A_e(n);
    thisP9 = solve(eqn,x);
    if isempty(thisP9)
        P_9(n)=0;
    else
        P_9(n)=double(thisP9(1));
    end
end