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Program Modelling Concepts

**Modelling Processes for Software Analysis before Software Implementation**__Data Flow Graph (DFG)__- Data Flow Graph (DFG) as the name says only the data which is flowing in to a process taken into account.
**for example** going to a bank for depositing the cash includes the data 1) input is **account number **and 2) output data is **balance in the account. ** - Other examples: Finding the average marks scored by a student: the input data is grades or marks scored and output data is the average grades or marks. the process is the (sum/total number of subjects).
- usually the input data is fed in to a process and output data comes after processing the input data.
- DFG does not have any conditions within it, but has only data entry point and one data output entry point.
- When there is only one set of values of each of the inputs and only one set of values of the outputs for the given input, a DFG is also known to be Acrylic Data Flow Graph (ADFG)
- Example of ADFG: In an FIR Filter with
- y6=a0x6+a1x5+......+a6x0, in this equation for a FIR filter, there are 7 multiplication units , each consumes only one memory to store and has only one value, i.e x0.....x6 has one value and a0, a1....a6 each has one value, so a0x6,.......a6x0 each will also have one value and y6 is also have only one value. So this example comes under
**ADFG** - But the examples of Non Acrylic DFG includes 1) A status flag setting in a device 2) Input as per output condition of the previous process