Improve CreateSingleValuedWorkspace docs and add usage tests.

Refs #9574

Code/Mantid/Framework/Algorithms/inc/MantidAlgorithms/CreateSingleValuedWorkspace.h

@@ -54,8 +54,8 @@ class DLLExport CreateSingleValuedWorkspace : public Mantid::API::Algorithm
   virtual ~CreateSingleValuedWorkspace() {}
   /// Algorithm's name
   virtual const std::string name() const { return "CreateSingleValuedWorkspace"; }
-    ///Summary of algorithms purpose
-    virtual const std::string summary() const {return "Creates a 2D workspace with a single value contained in it.";}
+  ///Summary of algorithms purpose
+  virtual const std::string summary() const {return "Creates a 2D workspace containing a single X, Y & E value.";}
 
   /// Algorithm's version
   virtual int version() const { return (1); }

Code/Mantid/docs/source/algorithms/CreateSingleValuedWorkspace-v1.rst

@@ -10,7 +10,65 @@ Description
 -----------
 
 Creates a 2D workspace that contains a single value and an optional
-error value. This is useful if, for example, there is a need to multiply
-(or divide etc) a workspace by a single value.
+error value. This was traditionally used for doing binary operations between
+a workspace and a single value. However, now that the Python access allows
+the standard binary operations with workspaces & single numbers, the requirement
+for this algorithm is almost gone.
+
+One use case for which it will be required is when performing operations using only
+the MantidPlot GUI point-and-click approach.
+
+Usage
+-----
+
+**Workspace with single y value and zero error:**
+
+.. testcode::
+
+   five = CreateSingleValuedWorkspace(5)
+
+   print "Number of histograms:",five.getNumberHistograms()
+   print "Length of y array:",len(five.readY(0))
+   print "Length of e array:",len(five.readE(0))
+   print "Length of x array:",len(five.readX(0))
+
+   print "y value:",five.readY(0)
+   print "e value:",five.readE(0)
+
+Output:
+
+.. testoutput::
+
+   Number of histograms: 1
+   Length of y array: 1
+   Length of e array: 1
+   Length of x array: 1
+   y value: [ 5.]
+   e value: [ 0.]
+
+**Workspace with single y and e value:**
+
+.. testcode::
+
+   five = CreateSingleValuedWorkspace(5, 0.1)
+
+   print "Number of histograms:",five.getNumberHistograms()
+   print "Length of y array:",len(five.readY(0))
+   print "Length of e array:",len(five.readE(0))
+   print "Length of x array:",len(five.readX(0))
+
+   print "y value:",five.readY(0)
+   print "e value:",five.readE(0)
+
+Output:
+
+.. testoutput::
+
+   Number of histograms: 1
+   Length of y array: 1
+   Length of e array: 1
+   Length of x array: 1
+   y value: [ 5.]
+   e value: [ 0.1]
 
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