PHYS 105: Notes on Homework 1

The actual programming involved in this homework should not pose too many problems -- that is, you should be able to construct simple working programs to sum the series and evaluate the functions in the three problems without too much difficulty. However, a few aspects may be unfamiliar -- specifically, compiling the program (if you use C++) and doing the graphics.

For compilation of a C++ program, please read the following page on the course web site:
C++ Compilation
The C++ compiler on our system is called g++. In most cases all you will need to do is
- create a file called (e.g.) program.cc containing your C++ code. Then
- in the terminal window, type
```
    g++ program.cc -o program
```
  to create an executable version of your program. Finally,
- run the program by typing its name
```
    ./program
```
In Python, simply create a file called program.py containing your Python code, then type
```
    python program.py
```
to run it.
The simplest way to make a graph is to create columns of numbers, then use the gpl program to plot it. More information can be found here on the course web site.
Simply put, if you want to graph two functions, f(x) and g(x), say, then write the functions in your program and include (in C++) a loop of the form
```
    for (x = xmin; x <= xmax; x += dx)
        cout << x << " " << f(x) << " " << g(x) << endl;
```
An equivalent Python code fragment might be
```
    x = xmin
    while x <= xmax:
        print x, f(x), g(x)
	x += dx
```
To plot the graphs on the screen, type
```
    ./program | gpl -c 1 2 3
```
or
```
    python program.py | gpl -c 1 2 3
```
To save the graphs in a file, type
```
    ./program | gpl -c 1 2 3 -P > graph.ps
```
(and similarly for the Python code).
Don't worry about the details of getting multiple plots on a single graph -- we'll cover that later.
The gpl program was developed to simplify the plotting process, especially in C++, but note that Python has several very capable packages that can handle graphics internally. For more information on two of them, try googling "python gnuplot" or "python matplotlib." Feel free to use these packages (or another) if you like.
Submitting homeworks by e-mail.
The current course syllabus calls for homeworks to be submitted as hard-copy. However, as an experiment, you can if you wish submit Homework 1 by e-mail. To do so, please do the following.
- In a separate folder (HW1, say), place the following
  - a header file (in .doc, .pdf, .txt, or other standard format) describing the contents of the directory and providing answers to the specific problems posed in the homework problems
  - C++ or Python programs solving the problems
  - PostScript (.ps) or PDF (.pdf) graphs, as requested, with content and axes clearly marked (see the gpl documentation for details)
- Bundle the folder into a zip archive with
```
    zip -r HW1.zip HW1
```
  or into a tar archive with
```
    tar cf HW1.tar HW1
```
  and e-mail the archive to me.