What tag did I miss when creating?

Question

MATLAB

In general, it gives an error:

Error using bellmf (line 4) Not enough input arguments.

I understand that I wrote this line incorrectly, but you can show what is wrong

function mu=bellmf(x, params)
c=-2;
a=params(1);
mu=1./(1+exp(-(power*(a(x-c)))));

I do this formula:

Answer 1

I think the last line should be:
mu=1./(1+exp(-a * (xc) ));