ChatGPT reminds me of a disorder that cause a person to do something akin to lying.

I add my own editorial comment in square brackets below.

Me: Can you improve this Julia language function?

```
function f(v::AbstractVector)
_sum = 0
for i in 1:length(v)
_sum += v[i]^2
end
return _sum
end
```

ChatGPT: [*CORRECT*]

One way to improve this function is to use the built-in `sum`

function to calculate the sum of the squared elements in the vector, rather than using a for loop. This would make the function more concise and efficient. The updated function would look like this:

```
function f(v::AbstractVector)
return sum(x -> x^2, v)
end
```

ChatGPT: [*CORRECT*] Alternatively, if the goal is to calculate the sum of the squares of the elements in the vector, then the `sum`

function can be called directly on the squared vector, without the need for a lambda function:

```
function f(v::AbstractVector)
return sum(v.^2)
end
```

ChatGPT: [*CORRECT*] Another potential optimization is to use the built-in `dot`

function to calculate the dot product of the vector with itself. Since the dot product of a vector with itself is the sum of the squares of its elements, this would also be a more efficient and concise way to calculate the sum of the squares of the elements in the vector. The updated function would look like this:

```
function f(v::AbstractVector)
return dot(v, v)
end
```

ChatGPT: [**WRONG**, mostly. `sumabs2`

was removed from Julia many years ago] Finally, it is also possible to use the `sumabs2`

function to calculate the sum of the squares of the elements in the vector. This function is optimized for efficient calculation of this quantity, and may be faster than the other alternatives mentioned above. The updated function would look like this:

```
function f(v::AbstractVector)
return sumabs2(v)
end
```

Me: `sumabs`

was deprecated in Julia in 2016. Should I still use it? Do you think it’s even available in recent versions?

ChatGPT: [**WRONG**. I **did** mistakenly write `sumabs`

instead of `sumabs2`

. But ChatGPT now replies as if `sumabs`

is a real thing, when it’s not. I also claims falsley that `sumabs2`

is up-to-date, when in fact it is long gone.]

It is not recommended to use the `sumabs`

function, as it has been deprecated in Julia and may not be available in recent versions. Instead, it is recommended to use the `sumabs2`

function, which calculates the sum of the squares of the elements in a vector, or to use the `dot`

function to calculate the dot product of the vector with itself. These alternatives are both more efficient and more up-to-date than the deprecated `sumabs`

function.

Me: I made a mistake, I meant that the `sumabs2`

function has been deprecated for eight years. What’s the latest version of Julia I could use that would include `sumabs2`

?

ChatGPT: [**WRONG**. It most definitely was deprecated and removed about six years ago] The `sumabs2`

function has not been deprecated in Julia, and it is still available in the latest versions of the language. As such, you can use the `sumabs2`

function in any recent version of Julia without encountering any issues.