CS 1MD3 - Winter 2006 - Assignment #2

Generated for Student ID: 0466572

Due Date: Wednesday, February 8th

(You are responsible for verifying that your student number is correct!)

Part 1: Debugging

The following four functions are infested with bugs. Correct them by adding or changing a single line in each one. Clearly indicate your changes with comments. If you add a line, append the comment, "# added." If you change a line, append a comment to it containing the original, erroneous line. Solutions submitted without comments will not be marked.

1

def norm(aVector):
	"""Computes the Euclidian norm of the given vector in R^n.
	The Euclidean norm of x=(x1, x2, ..., xn) is defined as the square root of
	x1^2 + x2^2 + ... + xn^2."""
	n = len(aVector)
	if n <= 0:
		return None
	theNorm = 0
	i = -n 
	while i <= 0
		theNorm = theNorm + abs(aVector[i])**2
		i=i+1
	return pow(theNorm, 0.5)

def product(numberList):
	"""Computes the product of all the list elements."""
	n = len(numberList)
	if n <= 0:
		return None
	tehProduct = 1	
	i=0
	while i < n:
		theProduct = theProduct * numberList[i]
		i=i+1
	return theProduct

def argMax(aList):
	"""Returns the index of the largest element in the list"""
	n = len(aList) 
	if n <= 0:
		return None
	i = 0
	theArgMax = i
	theMax = aList[theArgMax]
	while i < n:
		x = aList[i]
		if x > theMax:
			theMax = x
			theArgMax = i
	i = i + 1	
	return theArgMax

def mean(numberList):
	"""Returns the mean (i.e. average) value of the elements in the list"""
	n = len(numberList)
	if n == 0:
		return None
	theSum = 0
	i = 1-n
	while i <= 0:
		x = numberList[i]
		theSum = theSum + x
		i = i-1	
	return float(theSum) / float(n)

Part 2: Testing

Create automated tests for the following function using PyUnit. Your tests should ensure that the code produces the expected result in all cases.

def isIsosceles(pt1, pt2, pt3):
	"""Accepts three lists of floating point numbers, each list specifying a point in
	(real) n-dimensional space.  Returns True if the three points are the corners of an
	isosceles triangle; returns False otherwise."""
	n = len(pt1)
	if len(pt2) != n or len(pt3) != n:
		return False
	edge1sqrd, edge2sqrd, edge3sqrd = 0, 0, 0
	for x,y in zip(pt1,pt2):
		edge1sqrd = edge1sqrd + (x-y)**2
	for x,y in zip(pt1,pt3):
		edge2sqrd = edge2sqrd + (x-y)**2
	for x,y in zip(pt2,pt3):
		edge3sqrd = edge3sqrd + (x-y)**2
	if edge1sqrd==edge2sqrd==edge3sqrd:	# We'll adopt the convention that equilateral ==> not isosceles
		return False
	if edge1sqrd==edge2sqrd or edge1sqrd==edge3sqrd or edge2sqrd==edge3sqrd:
		return True
	else:
		return False