This class represents the elementwise operation \(\log(1 + e^x)\). This is a special case of log(sum(exp)) that evaluates to a vector rather than to a scalar, which is useful for logistic regression.

```
Logistic(x)
# S4 method for Logistic
to_numeric(object, values)
# S4 method for Logistic
sign_from_args(object)
# S4 method for Logistic
is_atom_convex(object)
# S4 method for Logistic
is_atom_concave(object)
# S4 method for Logistic
is_incr(object, idx)
# S4 method for Logistic
is_decr(object, idx)
# S4 method for Logistic
.grad(object, values)
```

- x
An Expression or numeric constant.

- object
A Logistic object.

- values
A list of numeric values for the arguments

- idx
An index into the atom.

`to_numeric(Logistic)`

: Evaluates`e^x`

elementwise, adds one, and takes the natural logarithm.`sign_from_args(Logistic)`

: The atom is positive.`is_atom_convex(Logistic)`

: The atom is convex.`is_atom_concave(Logistic)`

: The atom is not concave.`is_incr(Logistic)`

: The atom is weakly increasing.`is_decr(Logistic)`

: The atom is not weakly decreasing.`.grad(Logistic)`

: Gives the (sub/super)gradient of the atom w.r.t. each variable

`x`

An Expression or numeric constant.