PHYS 252

Assignment #4
[5 pts, due 2pm, April 10]

1. Here is the skeleton of a general purpose integrator of ordinary differential equations: integ.c. Fill in the code only where I marked XXX. The final code should run and reproduce question 2 from assignment 3. Note that 'step' calls 'derivs', and I've coded in the 'derivs' for you. You will hopefully be able to use this code in future assignments for solving many different ODE's with different methods.
2. Use your general purpose integrator from question 1 to integrate equations 1.12 in the book (see problem 1.5 [pdf]), with initially N_A=100, N_B=0, tau=1. Note: you should only have to modify the functions 'initialize' and 'derivs'.
3. For this question, you have two options. Either finish working through the square-bracketed sections of the Online C tutorial below, or do problem 1.6 in the book with your general purpose integrator. If you are doing the Online C tutorial, write on your solution the sections of the Online C Tutorial you've done.

Following is a list of chapters in the Online C Tutorial. I recommend you do the pages enclosed in square brackets, because these are the most important pages for this course. The remaining sections are not necessary, but are still worth doing for learning C.

• Introduction [c_000-c_005]
• Declaring Variables [c_006-c_009]
• Preprocessor Statements [c_010-c_012]
• Arithmetic Operators [c_013-c_015]
• Programming Style [c_015a]
• Keyboard Input [c_016-c_017]
• Relational Operators [c_018]
• For and while loops [c_019-c_022]
• If, if else, relational operators [c_024-c_027b, c_029]
• Switch/case
• String and character handling
• Data validation examples
• Conditional expression operator
• Arrays [c_034-c_041]
• Functions [c_042-c_050]
• Additional assignment operator [c_051-c_052, c_054]
• Sample programs so far
• Handling user input and Validation
• Formatters for printf() and scanf(), bit operations
• Structures
• Data conversion with itoa() and atoi()
• Files [c_069]
• Pointers [c_076-c_077, c_0771]
• Linked Lists
• Dynamic Memory Allocation
• Preprocessor Statements, Macros, Conditional Compilation, typedef
• Eumerated Data Types
• Unions
• Register based variables, null statements and strings
• Command Line Arguments
• Pointers to functions
• Formatters for characters and strings
• System Calls

• To learn more about pointers, you can go through this pointer tutorial. It gets to more advanced topics than are needed in this course. But it is useful if you want to learn more about pointers. (Chapter 5 requires learning about structures. You could either skip it, or learn about structures first.)