Document missing functions

docs/api/srfi/132.md

@@ -15,8 +15,12 @@ See the [SRFI document](http://srfi.schemers.org/srfi-132/srfi-132.html) for mor
 - [`list-stable-sort`](#list-stable-sort)
 - [`vector-delete-neighbor-dups!`](#vector-delete-neighbor-dups-1)
 - [`vector-delete-neighbor-dups`](#vector-delete-neighbor-dups)
+- [`vector-find-median`](#vector-find-median)
+- [`vector-find-median!`](#vector-find-median-1)
 - [`vector-merge!`](#vector-merge-1)
 - [`vector-merge`](#vector-merge)
+- [`vector-select!`](#vector-select-1)
+- [`vector-separate!`](#vector-separate-1)
 - [`vector-sort!`](#vector-sort-1)
 - [`vector-sort`](#vector-sort)
 - [`vector-sorted?`](#vector-sorted)
@@ -95,6 +99,18 @@ This procedure does not alter its input vector, but rather newly allocates and r
 
 This procedure reuses its input vector to hold the answer, packing it into the index range [start, newend), where newend is the non-negative exact integer that is returned as its value. The vector is not altered outside the range [start, newend).
 
+# vector-find-median
+
+    (vector-find-median < v knil [ mean ])
+
+This procedure does not alter its input vector, but rather newly allocates a vector to hold the intermediate result. Runs in O(n) time.
+
+# vector-find-median!
+
+    (vector-find-median! < v knil [ mean ])
+
+This procedure reuses its input vector to hold the intermediate result, leaving it sorted, but is otherwise the same as vector-find-median. Runs in O(n ln n) time.
+
 # vector-merge
 
     (vector-merge < v1 v2 [ start1 [ end1 [ start2 [ end2 ] ] ] ])
@@ -111,6 +127,18 @@ This procedure writes its result into vector `to`, beginning at index `start`, f
 
 All four merge operations are stable: an element of the initial list `lis1` or vector `v1` will come before an equal-comparing element in the second list `lis2` or vector `v2` in the result.
 
+# vector-select!
+
+    (vector-select! < v k [ start [ end ] ] )
+
+This procedure returns the `k`th smallest element (in the sense of the `<` argument) of the region of a vector between `start` and `end`. Elements within the range may be reordered, whereas those outside the range are left alone. Runs in `O(n)` time.
+
+# vector-separate!
+
+    (vector-separate! < v k [ start [ end ] ] )
+
+This procedure places the smallest `k` elements (in the sense of the `<` argument) of the region of a vector between `start` and `end` into the first `k` positions of that range, and the remaining elements into the remaining positions. Otherwise, the elements are not in any particular order. Elements outside the range are left alone. Runs in `O(n)` time. Returns an unspecified value.
+
 # vector-sort
 
     (vector-sort < v [ start [ end ] ])