DOCSP-13855-mod-has-inconsistent-rounding

Author: ianf-mongodb

source/reference/operator/query/mod.txt

@@ -117,3 +117,62 @@ operator with an array that contains four elements:
    	"$err" : "bad query: BadValue malformed mod, too many elements",
    	"code" : 16810
    }
+
+Floating Point Arguments
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``$mod`` expression rounds decimal input towards zero.
+
+The following examples demonstrate this behavior:
+
+.. example::
+
+   Input query:
+
+   .. code-block:: javascript
+
+      db.inventory.find( { qty: { $mod: [ 4.0, 0 ] } } )
+
+   Results:
+
+   .. code-block:: javascript
+      :copyable: false
+
+      { _id: 1, item: 'abc123', qty: 0 }
+      { _id: 3, item: 'ijk123', qty: 12 }
+
+.. example::
+
+   Input query:
+
+   .. code-block:: javascript
+
+      db.inventory.find( { qty: { $mod: [ 4.5, 0 ] } } )
+
+   Results:
+
+   .. code-block:: javascript
+      :copyable: false
+
+      { _id: 1, item: 'abc123', qty: 0 }
+      { _id: 3, item: 'ijk123', qty: 12 }
+
+.. example:: 
+
+   Input query:
+
+   .. code-block:: javascript
+
+      db.inventory.find( { qty: { $mod: [ 4.99, 0 ] } } )
+
+   Results:
+
+   .. code-block:: javascript
+      :copyable: false
+
+      { _id: 1, item: 'abc123', qty: 0 }
+      { _id: 3, item: 'ijk123', qty: 12 }
+
+Each query applies ``4`` to the $mod function regardless of 
+decimal points, resulting in the same result set.
+