Add documentation for reverse()

src/functions-reference/array_operations.Rmd

@@ -3,10 +3,11 @@
 ```{r results='asis', echo=FALSE}
 if (knitr::is_html_output()) {
 cat(' * <a href="array-reductions.html">Reductions</a>\n')
-cat(' * <a href="array-size-and-dimension-function.html">Array Size and Dimension Function</a>\n')
-cat(' * <a href="array-broadcasting.html">Array Broadcasting</a>\n')
-cat(' * <a href="array-concatenation.html">Array Concatenation</a>\n')
+cat(' * <a href="array-size-and-dimension-function.html">Array size and dimension function</a>\n')
+cat(' * <a href="array-broadcasting.html">Array broadcasting</a>\n')
+cat(' * <a href="array-concatenation.html">Array concatenation</a>\n')
 cat(' * <a href="sorting-functions.html">Sorting functions</a>\n')
+cat(' * <a href="reversing-functions.html">Reversing functions</a>\n')
 }
 ```
 
@@ -178,7 +179,7 @@ The squared Euclidean distance between x and y
 `real` **`squared_distance`**`(row_vector x, row_vector[] y)`<br>\newline
 The Euclidean distance between x and y
 
-## Array Size and Dimension Function
+## Array size and dimension function
 
 The size of an array or matrix can be obtained using the `dims()`
 function.  The `dims()` function is defined to take an argument
@@ -236,7 +237,7 @@ can be any type, but the size is just the size of the top level array,
 not the total number of elements contained. For example, if `x` is of
 type `real[4,3]` then `size(x)` is 4.
 
-## Array Broadcasting {#array-broadcasting}
+## Array broadcasting {#array-broadcasting}
 
 The following operations create arrays by repeating elements to fill
 an array of a specified size.  These operations work for all input
@@ -312,7 +313,7 @@ After the assignment to `b`, the value for `b[j,k,m,n]` is equal to
 `a[m,n]` where it is defined, for `j` in `1:3`, `k` in `1:4`, `m` in
 `1:5`, and `n` in `1:6`.
 
-## Array Concatenation {#array-concatenation}
+## Array concatenation {#array-concatenation}
 
 <!-- T; append_array; (T x, T y); -->
 \index{{\tt \bfseries append\_array }!{\tt (T x, T y): T}|hyperpage}
@@ -409,3 +410,16 @@ Number of components of v less than v[s]
 `int` **`rank`**`(int[] v, int s)`<br>\newline
 Number of components of v less than v[s]
 
+## Reversing functions {#reversing-functions}
+
+Stan provides functions to create a new array by reversing the order of
+elements in an existing array. For example, if `v` is declared as a real
+array of size 3, with values
+\[ \text{v} = (1,\, -10.3,\, 20.987), \] then
+\[ \mathrm{reverse(v)} = (20.987,\, -10.3,\, 1). \]
+
+<!-- T[]; reverse; (T[] v); -->
+\index{{\tt \bfseries reverse }!{\tt (T[] v): T[]}|hyperpage}
+
+`T[]` **`reverse`**`(T[] v)`<br>\newline
+Return a new array containing the elements of the argument in reverse order.

src/functions-reference/matrix_operations.Rmd

@@ -16,6 +16,7 @@ cat(' * <a href="softmax.html">Special Matrix Functions</a>\n')
 cat(' * <a href="covariance.html">Covariance Functions</a>\n')
 cat(' * <a href="linear-algebra-functions-and-solvers.html">Linear Algebra Functions and Solvers</a>\n')
 cat(' * <a href="sort-functions.html">Sort Functions</a>\n')
+cat(' * <a href="reverse-functions.html">Reverse Functions</a>\n')
 }
 ```
 
@@ -1544,8 +1545,8 @@ The singular values of A in descending order
 
 ## Sort Functions
 
-see section [sorting functions](#sorting-functions) for examples of how the functions
-work.
+See the [sorting functions section](#sorting-functions) for examples of how
+the functions work.
 
 <!-- vector; sort_asc; (vector v); -->
 \index{{\tt \bfseries sort\_asc }!{\tt (vector v): vector}|hyperpage}
@@ -1611,3 +1612,16 @@ Number of components of v less than v[s]
 `int` **`rank`**`(row_vector v, int s)`<br>\newline
 Number of components of v less than v[s]
 
+## Reverse Functions {#reverse-functions}
+
+<!-- vector; reverse; (vector v); -->
+\index{{\tt \bfseries reverse }!{\tt (vector v): vector}|hyperpage}
+
+`vector` **`reverse`**`(vector v)`<br>\newline
+Return a new vector containing the elements of the argument in reverse order.
+
+<!-- row_vector; reverse; (row_vector v); -->
+\index{{\tt \bfseries reverse }!{\tt (row_vector v): row_vector}|hyperpage}
+
+`row_vector` **`reverse`**`(row_vector v)`<br>\newline
+Return a new row vector containing the elements of the argument in reverse order.