Explain in detail about Functional Modelling.
-  This model explains the computations that take place within a system. 
-  This model is useful when the transformation from the inputs to outputs is difficult. 
-  The functional model of a system can be shown by a data Flow Diagram (DFD). 
Data Flow Diagrams/Data Flow Graph/Bubble chart
-  A DFD is a graphical shown that depicts the information flow and the transforms that are applied as the data move from input to output. 
-  Level 0 DFD also known as fundamental system model or context model shows the whole software as a single bubble with input and output data indicated by incoming and outgoing arrow