The '''grade up''' primitive is used to get the indices of an array that would sort it in ascending order.
[[Category:Verbs]]
Since grading is not the same as sorting, a general idiom used to sort arrays is <code>{x(<x)}</code> or other equivalent.
[[Category:Operator verbs]]
[[Category:Primitives]]
Grade primitives generally use a [https://en.wikipedia.org/wiki/Category:Stable_sorts stable sort], which means that an ascending grade may not always be the inverse of a descending grade.
For numeric arrays:
<pre>
<34 -1 0 67 32767
1 2 0 3 4</pre>
Grading of string arrays largely depends upon the implementation.
For ngn/k(K6), groups by length and sorts each individual group: