Hi, everyone.I have problem to solve the following question.

clc

clear all

I = 50;

eps1 = 10^-6;

eps2 = 10^-6;

fmax = 20 * 10^9;

s = normrnd(1000, 100, I) * 8000 ;

cvx_begin

variable a(I) nonnegative

variable fs(I) nonnegative

variable b(I) nonnegative

%variable m(I)

```
maximize sum(a)
subject to
0 <= a <= 1;
beta = inv_pos(b+eps1);
%abs(a) .* beta;
expression mu(I)
mu = diag(a * beta.');
```

cvx_end

Error using cvx_throw (line 22)

Disciplined convex programming error:

Invalid quadratic form(s): not a square.

Error in bsxfun (line 11)

Error in * (line 42)

Error in sim (line 25)

mu = diag(a * beta.’);

I need help