Invalid expression during a function handle

I am recieving the following error:

Invalid expression. Check for missing multiplication operator, missing or unbalanced delimiters, or other syntax error. To construct matrices, use brackets instead of parentheses.

This is the line that is causing the error:

Kernel = @x q.*(exp(-jk.*(sqrt(a^2 + (m1 - (x)).^2)))./(4*pi.*((sqrt(a^2 + (m1 - (x)).^2)).^5)))*((1+jk.*(sqrt(a^2 + (m1 - (x)).^2))).*(2*((sqrt(a^2 + (m1 - (x)).^2)).^2)-3.*(a^2))+((k*a.*(sqrt(a^2 + (m1 - (x)).^2))).^2));

The following variables have already been defined prior to this line:

q, jk, m1, k and a. The only variable is x.

I counted the parentheses, checked the multiplication operator, and I am not trying to construct a matrix.

Some background context:

This line is within 2 for loops. When I take off the function handle (@x) and set x = 1, the code runs without any errors. I plan on integrating this Kernel function and pass it to an array. The original equation is q*(exp(-jk*R)/(4*pi*(R^5)))*((1+jk*R)*(2*(R^2)-3*(a^2))+((k*a*R)^2)) but since the variable X is within R, I expanded R at each instance. R = sqrt(a^2 + (m1 - m2)^2)

Thank you guys in advance!

Answer 1

[Torsten]

Must read

Kernel = @(x) ...

instead of

Kernel = @x ...

[Allen Yau]

Thank you! Cant believe it was just this