Update FABADA.rst

Code/Mantid/docs/source/concepts/FABADA.rst

@@ -67,4 +67,20 @@ Parameters (*optional*)
   errors for each parameter (cost function is not included).
   This is output as a TableWorkspace.
 
+Usage
+-----
+
+**Example: A simple example**
+
+.. code-block:: python
+
+ws_data = Load(Filename='irs26176_graphite002_red.nxs')
+ws_res = Load(Filename='irs26173_graphite002_res.nxs')
+
+function_str = 'composite=Convolution,FixResolution=tue,NumDeriv=false;name=Resolution,Workspace=ws_res,WorkspaceIndex=0;(composite=CompositeFunction,NumDeriv=true;name=Lorentzian,Amplitude=1,PeakCentre=0.01,FWHM=0.5;name=Lorentzian,Amplitude=1,PeakCentre=0.01,FWHM=0.5)'
+minimizer_str = "FABADA,Chain Lengh=1000000,Steps between values=10,Convergence Criteria=0.01,PDF=pdf,Chains=chain,Converged chain=conv,Cost Function Table=CostFunction,Parameter Erros =Errors"
+
+Fit(Function = function_str,InputWorkspace=ws_data,WorkspaceIndex=3,StartX=-0.25,EndX=0.25,CreateOutput=True,Output = 'result',OutputCompositeMembers=True,MaxIterations=2000000, Minimizer=minimizer_str)   
+
+
 .. categories:: Concepts