Docs for rand/rang-range.

3.8/graphs-custom-pregel.md

@@ -674,7 +674,7 @@ that the parameters are bound to. Both can be accessed using their name via
 
 The reduce method executes a reducer function (lambda - required) on each element of the array or object.
 In general, it is being used to generate a single output value, yet it can be used to generate any supported
-types. 
+types.
 
 The lambda function accepts three parameters, the current index (which is either the
 position in an array, or the current key in case of an object), the value and the accumulator.
@@ -690,7 +690,7 @@ Addition of all array elements (initial accumulator / start value set to 100).
  ["quote", []],
  ["quote", ["key", "value", "accum" ]],
  ["quote",
- ["+", ["var-ref", "value"], ["var-ref", "accum"] ] 
+ ["+", ["var-ref", "value"], ["var-ref", "accum"] ]
  ]
  ],
  100
@@ -713,7 +713,7 @@ Explanation:
 3.) Iteration
  - Take result of the second iteration as accumulator value
  - Calculate and return the sum of 103 and 3
- - Return 106 as we've reached the end of our array 
+ - Return 106 as we've reached the end of our array
 ```
 
 Advanced example:
@@ -757,11 +757,14 @@ _random functions that fit no other category_
 ["min", numbers...]
 ["max", numbers...]
 ["avg", numbers...]
+["rand"]
+["rand-range", min, max]
 ```
 
 `string-cat` concatenates the given strings. `int-to-string` converts a integer
 to its decimal representation.
 `min`/`max`/`avg` computes the minimum/maximum/average of its values.
+`rand`/`rand-range` produces a pseudo random number uniformly distributed in `[0,1]`/`[min,max]`.
 
 ```js
 > ["string-cat", "hello", " ", "world"]
@@ -772,6 +775,10 @@ to its decimal representation.
  = 3
 > ["avg", 1, 2, 3]
  = 2
+> ["rand"]
+ = 0.8401877171547095
+> ["rand-range", 5, 7]
+ = 5.788765853638186
 ```
 
 #### Functional