4 design
- 1. Basic Scientific Programming Design Cycle 1
- 2. Binary Systems Data is stored in the computer in binary format. Bit:Binary digit, smallest unit to store 0: low voltage,false, off,… 1: high voltage, true, on,… Byte: 8-bits. Unit is used to express storage capacity. A byte represents 28=256 (0-255) 00000000 = 0 00000001 = 1 00000010 = 2 . . 11111111 = 255 2
- 3. Binary System The base in the binary system is (2) 1 KiloByte = 210 = 1024 Bytes 1 MegaByte= 220 = 1,048,576 Bytes 1 GigaByte = 230 = 1,073,741,824 B 000= 0* 22 + 0* 21 + 0* 20 = 0 001= 0* 22 + 0* 21 + 1* 20 = 1 . . 111= 1* 22 + 1* 21 + 1* 20 = 7 3
- 4. Design Cycle We write programs to help us solve problems. Program development process: 1) Problem Analysis and Specification. 2) Data Organization and Algorithm Design. 3) Program Coding 4) Execution and Testing. 4
- 5. Example /Step 1 Calculate the Area & Circumference of a circle of radius R=5. * The best approach is to generalize the problem; i.e for any value of R. Step 1: Problem Analysis and Specification Determine the Inputs ( Radius ). Determine the Outputs (Area, Circumference). 5
- 6. Example /Step 2 Step 2: Data Organization and Algorithm Design. In this step we need to know the formulas to calculate the Area and Circumference. (A = ᴨR2 , C = 2ᴨR). A possible algorithm Input: radius of Circle. Output: Area and Circumference. Enter the value of Radius. Calculate the Area(A) and Circumference(C). Display A, C. 6
- 7. Example /Step 3 Step 3: write a program to implement the algorithm. Program Circle Implicit None Real :: Radius, Area, Circum Real, Parameter :: pi = 3.141593 Print *, ‘Enter the radius of the circle’ Read *, Radius Area = pi * Radius**2 Circum= 2* pi * Radius Print *, ‘Area=‘, Area, ‘ Circumference=‘ , Circum End 7
- 8. Example /Step 4 Step 4: Execution and Testing 1) Compiling the code and correcting errors. 2) Executing the program, and trying different inputs to check if the algorithm is correct. 8
- 9. Errors Syntax Errors: Errors in the syntax of the language Ex: Print *, ‘Area = , Area. Logical Errors: Incorrect output(s) due to wrong algorithm Ex: Area = pi * Radius**3 Run-time Errors: Errors that occur while running the program. Ex: C = a/b if the user assigns the value 0 to b the a divide by zero error well occur, which will terminate the execution of the program. If the user enter another value for b the program will executer correctly. 9
- 10. Errors Syntax Errors: Errors in the syntax of the language Ex: Print *, ‘Area = , Area. Logical Errors: Incorrect output(s) due to wrong algorithm Ex: Area = pi * Radius**3 Run-time Errors: Errors that occur while running the program. Ex: C = a/b if the user assigns the value 0 to b the a divide by zero error well occur, which will terminate the execution of the program. If the user enter another value for b the program will executer correctly. 9