# Less than

(Redirected from Less)
Main article: Comparison function
For the set function, see Without.
 `<`

Less than (`<`) is a comparison function which tests whether the left argument is tolerantly less than and not equal to the right argument, returning 1 if this is the case and 0 otherwise. It is the negation of Greater than or Equal to (`≥`). Less-than Scan, which leaves only the first 1 in a Boolean vector set, is a notable pattern.

## Boolean function

When the arguments to Less than are Boolean, it is the converse nonimplication Boolean function:

`<` `0` `1`
`0` `0` `1`
`1` `0` `0`

It returns 1 only if the left argument is 0 and the right argument is 1, and is identical to Residue. Considered as a logical operation, it can be read as isn't, as opposed to.

Less-than Scan on a Boolean vector returns a vector which indicates the position of the first 1 in the argument, if any:

```      <\ 0 0 1 0 0 0 1 0
0 0 1 0 0 0 0 0
```

It is idiom 348, "First one", in the FinnAPL idiom library.