We have no idea what `t3`

or `t2`

are, nor how `t3_lb or t2_lb`

have been declared, if at all. Nor what error message or unexpected behavior you may have encountered.

If `t3`

is a MATLAB (not CVX) variable, i.e., has a numerical value, then `t3_lb(1,i)`

will have a numerical value. if `t3`

is a CVX variable or concave or affine CVX expression, then `inv_pos`

will not produce an error message, but the assignment to `t3_lb(1,i)`

requires `t3_lb`

to have been declared as an expr4ession holder (array) http://cvxr.com/cvx/doc/basics.html#assignment-and-expression-holders. Similarly with `t2 and t2_lb`

.

help inv_pos

inv_pos Reciprocal of a positive quantity.

inv_pos(X) returns 1./X if X is positive, and +Inf otherwise.

X must be real.

```
For matrices and N-D arrays, the function is applied to each element.
Disciplined convex programming information:
inv_pos is convex and nonincreasing; therefore, when used in CVX
specifications, its argument must be concave (or affine).
```