A good example of how to use functions is a modified version of assignment 2, available here.
In this example, we created a few helper functions, like the ones below to convert values between cartesian values and screen coordinates
#convert an x value from cartesian coordinates to screen coordinates def cartx(x): x = scale * x x = xcenter + x return x #convert an x value from cartesian coordinates to screen coordinates def carty(y): y = scale * y y = ycenter - y return y
The core of the program, that is, the drawing of the curve was also done using functions, as seen here
#Draw the curve defined by a,b,c and d from a beginning cartesian value to an end cartesian value #approximating by delta cartesian units def draw(a,b,c,d,begin,end,delta): x = begin while x < end: y = formula(a,b,c,d,x) y2 = formula(a,b,c,d,x+delta) print "line",cartx(x),carty(y),cartx(x+delta),carty(y2) x = x + delta sys.stdout.flush()