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CECS 229 Programming Assignment #6

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CECS 229 Programming Assignment #6

Submission Instructions:
To receive credit for this assignment you must submit to CodePost a Python script named pa6.py with your work by the due date.

Objectives:
Apply Gaussian Elimination to solve the system  Ax→=b→
.
Use Lp -norm to calculate the error in a solution given by applying Gaussian elimination.
Use the REF of the augmented matrix for the system  Ax→=b→
to determine if it has one solution, no solution, or infinitely-many solutions.
Determine the number of free variables that the system  Ax→=b→
has if it has infinitely-many solutions.
Determine whether a set of column-vectors is linearly dependent by forming and solving a system of the form  Ax→=0→
.
Problem 1
Copy-paste your implemented Matrix and Vec classes to the next cell. Then, complete the following tasks:

Add a method norm(self, p) to your Vec class so that if u is a Vec object, then u.norm(p) returns the  Lp
-norm of vector u. Recall that the  Lp
-norm of an  n
-dimensional vector  u→
is given by,  ||u||p=(∑ni=1|ui|p)1/p
. Input p should be of the type int. The output norm should be of the type float.
Add a method ref(self) that applies Gaussian Elimination to create and return the Row Echelon Form of the current matrix. The output must be of the type Matrix. The method should NOT modify the contents of self.rowsp or self.colsp. It should create and return a new Matrix object.
Add a method rank(self) to your Matrix class so that if A is a Matrix object, then A.rank() returns the rank of A.
import math

# Putting up Vector class from the previous assignment
class Vec:
def __init__(self, contents=[]):
“””
Constructor defaults to empty vector
INPUT: list of elements to initialize a vector object, defaults to empty list
“””
self.elements = contents
return

def __abs__(self):
“””
Overloads the built-in function abs(v)
returns the Euclidean norm of vector v
“””
# Variable to store the magnitude of the vector
magnitude_vector = 0
# Variable to store the sum of the squares of the elements in the vector
vector_squares = []
# Running through all the elements in the vector
for element in self.elements:
# Squaring the elements of the vector
sum_of_squares = element ** 2
# Appending the sum of the squares to the list
vector_squares.append(sum_of_squares)

# Square root of the sum of the squares of the elements in the vector
magnitude_vector = math.sqrt(sum(vector_squares))

return magnitude_vector  # Returning the magnitude of the vector

def __add__(self, other):
“””Overloads the + operator to support Vec + Vec
raises ValueError if vectors are not same length
“””
# Conditional Statement to check whether vectors are of same length
if len(self.elements) != len(other.elements):
raise ValueError(“Vectors must be same length”)
else:  # Run the following code once the condition is satisfied
# Variable to store the sum of the vectors
vector_sum = []
# Running through all the elements in the vector
for element in range(len(self.elements)):
# Adding the elements of the vectors together
sum_result = self.elements[element] + other.elements[element]
# Appending the sum of the elements to the list
vector_sum.append(sum_result)

# Converting the list to a vector
vector_sum = Vec(vector_sum)

return vector_sum  # Returning the sum of the vectors

def __sub__(self, other):
“””
Overloads the – operator to support Vec – Vec
Raises a ValueError if the lengths of both Vec objects are not the same
“””
# Conditional Statement to check whether vectors are of same length
if len(self.elements) != len(other.elements):
raise ValueError(“Vectors must be same length”)
else:  # Run the following code once the condition is satisfied
# Variable to store the difference of the vectors
vector_difference = []
# Running through all the elements in the vector
for element in range(len(self.elements)):
# Subtracting the elements of the vectors together
difference_result = self.elements[element] – other.elements[element]
# Appending the difference of the elements to the list
vector_difference.append(difference_result)

# Converting the list to a vector
vector_difference = Vec(vector_difference)

return vector_difference  # Returning the difference of the vectors

def __mul__(self, other):
“””Overloads the * operator to support
– Vec * Vec (dot product) raises ValueError if vectors are not same length in the case of dot product
– Vec * float (component-wise product)
– Vec * int (component-wise product)
“””
if type(other) == Vec:  # define dot product
# Conditional Statement to check whether vectors are of same length
if len(self.elements) != len(other.elements):
raise ValueError(“Vectors must be same length”)
else:  # Run the following code once the condition is satisfied
# Variable to store the dot product of the vectors
dot_product = 0
# Running through all the elements in the vector
for element in range(len(self.elements)):
# Multiplying the elements of the vectors each other
product_result = self.elements[element] * other.elements[element]
# Adding the product of the elements to the variable
dot_product += product_result

return dot_product  # Returning the dot product
elif type(other) == float or type(other) == int:  # scalar-vector multiplication
# Variable to store the result of scalar-vector multiplication
vector_product = []
# Running a loop through all the elements in the vector
for element in range(len(self.elements)):
# Multiplying the each elements in the vector to the scalar value
product_result = self.elements[element] * other
# Appending the product of the elements to the list
vector_product.append(product_result)

# Converting the list to a vector
vector_product = Vec(vector_product)

return vector_product  # Returning the scalar-vector multiplication

def __rmul__(self, other):
“””
Overloads the * operation to support
– float * Vec
– int * Vec
“””
# Variable to store another version of scalar-vector multiplication
vector_product = []
# Running a loop through all the elements in the vector
for element in range(len(self.elements)):
# Multiplying the each elements in the vector to the scalar value
product_result = self.elements[element] * other
# Appending the product of the elements to the list
vector_product.append(product_result)

# Converting the list to a vector
vector_product = Vec(vector_product)

return vector_product  # Returning the scalar-vector multiplication

def __str__(self):
“””returns string representation of this Vec object”””
return str(self.elements)  # does NOT need further implementation

“””Implementing norm(self, p) method”””
# Writing a method that returns the Lp-norm of the vector
def norm(self, p: int):
# Storing the result of sum of powers
sum_of_powers = 0
# Iterating through each element in the vector
for element in self.elements:
# Adding the sum of the powers of each element
sum_of_powers += abs(element) ** p # -> Summation of |x_i|^p
# Sotring the final result
lp_norm = sum_of_powers ** (1/p) # -> (Summation of |x_i|^p)^(1/p)
# Returning the final result
return lp_norm

# Putting up Matrix class from the previous assignment
class Matrix:

def __init__(self, rowsp):
self.rowsp = rowsp
self.colsp = self._construct_cols(rowsp)

# Constructing columns based on the number of row space
def _construct_cols(self, rowsp):
# Intializing column space as an empty list
colsp = []
# Setting Column number the same as the number of rows in the row space
cols_num = len(rowsp[0])
# Creating a list of empty lists for each column space
for _ in range(cols_num):
colsp.append([])

# Iterating through each row in the row space
for row in rowsp:
# Iterating through each entry in the row
for i, entry in enumerate(row):
# Appending the entry to the column space list
colsp[i].append(entry)
return colsp

def set_col(self, j, u):
”’
Changes the j-th column to be the list `u`.  If `u` is not the same length
as the existing columns, then the method raises a `ValueError` with the
message `Incompatible column length.`
”’
# Conditional statement to check u = length of the existing columns
if len(u) != len(self.colsp[0]):
# Raising ValueError if condition is not met
raise ValueError(“Incompatible column length.”)
else: # Running the code below if the condition is met
# Updating the first column space with the new column
self.colsp[j – 1] = u # -> j-1 because the index starts from 0
# Iterating through the row space
for i in range(len(self.rowsp)):
# Updating the row space with the new column
self.rowsp[i][j – 1] = u[i]

def set_row(self, i, v):
”’
Changes the i-th row to be the list `v`.  If `v` is not the same length
as the existing rows, then method raises a `ValueError` with the
message `Incompatible row length.`
”’
# Conditional statement to check v = length of the existing rows
if len(v) != len(self.rowsp[0]): # Starting from 0 because the index starts from 0
# Raising ValueError if condition is not met
raise ValueError(“Incompatible row length.”)
else: # Running the code below if the condition is met
# Updating the row space with the new row
self.rowsp[i – 1] = v
# Reconstructing the column space of the matrix
self.colsp = self._construct_cols(self.rowsp)

def set_entry(self, i, j, x):
”’
Changes the existing a_ij entry in the matrix to ‘x’.
”’
# Replacing the j-th entry in the row with x
self.rowsp[i – 1][j – 1] = x # -> i-1, j-1 because the index starts from 0
# Replacing the i-th entry in the column with x
self.colsp[j – 1][i – 1] = x # -> i-1, j-1 because the index starts from 0

# Returns the j-th column as a list
def get_col(self, j):
return self.colsp[j – 1] # -> j-1 because the index starts from 0

# Returns the i-th row as a list v
def get_row(self, i):
return self.rowsp[i – 1] # -> i-1 because the index starts from 0

# Returns the a_ij entry in the matrix
def get_entry(self, i, j):
return self.rowsp[i – 1][j – 1]

# Returns the list of vectors that make up the column space of the matrix object
def row_space(self):
return self.rowsp

# Returns the list of vectors that make up the row space of the matrix object
def col_space(self):
return self.colsp

def get_diag(self, k):
”’
Returns the k-th diagonal of the matrix as a list, where:
-> k = 0 returns the main diagonal
-> k > 0 returns the diagonal beginning at a_1(k+1)
-> k < 0 returns the diagonal beginning at a_-(k+1)1
”’
if k > 0:
# Storing diagonal entries beginning at a_1(k+1)
diag_3 = []
# Iterating through the row spaces from a_1(k+1)
for i in range(len(self.rowsp) – k):
# Appending the values based on the given kth value
diag_3.append(self.rowsp[i][i + k]) # -> 1(k+1) => (1)(k+1) => [i][i+k]
# Returning the diagonal values from a_1(k+1)
return diag_3
elif k < 0:
# Storing diagonal entries beginning at a_-(k+1)1
diag_2 = []
# Iterating through the row spaces from a_-(k+1)1
for i in range(len(self.rowsp) + k):
# Appending the values based on the given kth value
diag_2.append(self.rowsp[i – k][i]) # -> -(k+1)1 => (1-k)(1) => [i-k][i]
# Returning the diagonal values from a_-(k+1)1
return diag_2
else:
# Storing the main diagonal entries
main_diag = []
# Iterating through the row spaces
for i in range(len(self.rowsp)):
# Appending the values of the main diagonal
main_diag.append(self.rowsp[i][i])
# Returning the values of the main diagonal
return main_diag

def __add__(self, other):
if len(self.rowsp) != len(other.rowsp) or len(self.colsp) != len(other.colsp):
raise ValueError(“Incompatible matrix dimensions for addition.”)
else:
# Creating a list of empty lists for the sum of the matrices
matrix_sum = []
# Iterating through the row spaces
for i in range(len(self.rowsp)):
# Storing each reduced row in a list
row_sum = []
for j in range(len(self.colsp)):
# Appending the sum of the corresponding entries to row sum
row_sum.append(self.rowsp[i][j] + other.rowsp[i][j])
# Appending the row sum to the matrix sum
matrix_sum.append(row_sum)
# Returning the matrix sum as a Matrix object
return Matrix(matrix_sum)

def __sub__(self, other):
if len(self.rowsp) != len(other.rowsp) or len(self.colsp) != len(other.colsp):
raise ValueError(“Incompatible matrix dimensions for subtraction.”)
else:
# Creating a list of empty lists for the difference of the matrices
matrix_diff = []
# Iterating through the row spaces
for i in range(len(self.rowsp)):
# Storing each reduced row in a list
row_diff = []
for j in range(len(self.colsp)):
# Appending the difference of the corresponding entries to row difference
row_diff.append(self.rowsp[i][j] – other.rowsp[i][j])
# Appending the row difference to the matrix difference
matrix_diff.append(row_diff)
# Returning the reduced matrix as a Matrix object
return Matrix(matrix_diff)

def __mul__(self, other):
if type(other) == float or type(other) == int:
# Storing the product of matrix-scalar multiplication
scalar_mult_matrix = []
# Iterating through each row in the row space
for final_matrix_row in self.rowsp:
# Storing the each scaled row in a list
scaled_row = []
# Going through each element in the row
for element in final_matrix_row:
scaled_element = element * other # Mulitplying each element with the scalar value
scaled_row.append(scaled_element) # Appending the scaled product into the scaled row
# Appending the scaled rows to the scaled matrix
scalar_mult_matrix.append(scaled_row)
return Matrix(scalar_mult_matrix) # Returning a scaled matrix as a Matrix object
elif type(other) == Matrix: # –> If the other object is a matrix
# Checking if dimensions of the matrices match or not
if len(self.rowsp[0]) != len(other.rowsp):
raise ValueError(“Dimension mismatch for multiplication.”)
else:
# Array to store the product of the matrices
product_of_matrices = []
# Iterating through the rows of the first matrix
for num in range(len(self.rowsp)):
# Storing the product of each row of the first matrix with the columns of the second matrix
final_matrix_row = []
# Iterating through the columns of the other matrix
for column in range(len(other.colsp)):
# Storing the sum of the product of each row
matrix_sum = 0
# Iterating through the first index of the other matrix’s column
for l in range(len(other.colsp[0])):
self_matrix_mul = self.rowsp[num][l] # Storing the multiplication of first matrix
other_matrix_mul = other.rowsp[l][column] # Storing the multiplication of the second matrix
matrix_sum += self_matrix_mul * other_matrix_mul # Adding the products of the two matrices’ rows
# Appending the matrix sum to final matrix row
final_matrix_row.append(matrix_sum)
# Appending the final matrix rows to the final matrix product
product_of_matrices.append(final_matrix_row)
return Matrix(product_of_matrices) # Returning the product of matrices as a Matrix object
elif type(other) == Vec: # If the other object is a vector
# Storing the product of matrix-vector in a list
matrix_vector_product = []
# Iterating through the rows of the matrix
for matrix_row in range(len(self.rowsp)):
# Storing the sum of the product of each row
mat_vec_product = 0
# Iterating through each number in the matrix row
for num in range(len(self.rowsp[matrix_row])):
# Adding the products of the matrix row and the vector
mat_vec_product += self.rowsp[matrix_row][num] * other.elements[num]
matrix_vector_product.append(mat_vec_product) # Appending the matrix-vector product to the list
return Vec(matrix_vector_product) # Returning the matrix-vector product as a Vec object
else:
print(“ERROR: Unsupported Type.”)
return

def __rmul__(self, other):
if type(other) == float or type(other) == int:
return self.__mul__(other)
else:
print(“ERROR: Unsupported Type.”)
return

# Returns a formatted string representing the matrix entries as
def __str__(self):
“””prints the rows and columns in matrix form “””
mat_str = “”
for row in self.rowsp:
mat_str += str(row) + “\n”
return mat_str

def __eq__(self, other):
“””overloads the == operator to return True if
two Matrix objects have the same row space and column space”””
return self.row_space() == other.row_space() and self.col_space() == other.col_space()

def __req__(self, other):
“””overloads the == operator to return True if
two Matrix objects have the same row space and column space”””
return self.row_space() == other.row_space() and self.col_space() == other.col_space()

“””Implementing ref(self) method”””
# Writing a method that returns the reduced row echelon form of the matrix
def ref(self):
# Creating a copy of the matrix
matrix_copy = []
# Iterating through each row in the matrix
for row in self.rowsp:
# An temporary list to store the elements of the row
new_row = []
# Iterating through each element in the row
for element in row:
# Appending the element to the new row
new_row.append(element)
# Appending the new row to the matrix copy variable
matrix_copy.append(new_row)

# Storing the total number of rows and columns in the matrix
num_rows = len(matrix_copy)
num_cols = len(matrix_copy[0])

# Making non-square matrices square by adding zero rows or columns as needed
if num_rows != num_cols:
# Checks if the number of rows < the number of columns
if num_rows < num_cols:
# Iterating through the number of columns – number of rows
for i in range(num_cols, num_rows):
# Creating a zero row
zero_row = [0] * num_cols
# Appending the zero row to the matrix copy
matrix_copy.append(zero_row)
else: # –> If the number of rows > the number of columns
# Iterating through the number of rows – number of columns
for i in range(num_cols, num_rows):
# Creating a zero column
zero_col = [0] * num_rows
# Iterating through the number of rows
for j in range(num_rows):
# Appending the zero column to the matrix copy
matrix_copy[j].append(zero_col[j])

# Creating a variable to store the pivot column
row_pivot = 0

# Iterating through each column in the matrix
for j in range(num_cols):
# Finding the 1st non-zero entry in the j-th column below the pivot row
for i in range(row_pivot, num_rows):
# Checking if the entry is non-zero
if matrix_copy[i][j] != 0:
# Swapping the rows if the entry is zero
matrix_copy[row_pivot], matrix_copy[i] = matrix_copy[i], matrix_copy[row_pivot]
break
# Making of all the entries bwlow the pivot row zero
for i in range(row_pivot + 1, num_rows):
# Checking if the entry is non-zero
if matrix_copy[i][j] != 0:
# Creating a variable to store the factor value
factor = matrix_copy[i][j] / matrix_copy[row_pivot][j]
# Iterating through each element in the row
# Alternative -> matrix_copy[i] = [matrix_copy[i][k] – scalar * matrix_copy[row_pivot][k] for k in range(num_cols)]
new_row = []
for k in range(num_cols):
new_element = matrix_copy[i][k] – (factor * matrix_copy[row_pivot][k])
new_row.append(new_element)
# Replacing the row with the new row
matrix_copy[i] = new_row
# Moving to the next pivot row
row_pivot += 1
# Checking if the pivot row is the last row
if row_pivot == num_rows:
break
# Returning the reduced row echelon form of a matrix
return Matrix(matrix_copy)

“””Implementing rank(self) method”””
# Writing the method that returns the rank of the matrix
def rank(self):
# Converting input Matrix into reduced row echelon form
ref_matrix = self.ref()
# Creating a variable to store the rank of the matrix
rank = 0
# Storing total number of non-zero rows and columns in the matrix
non_zero_rows = 0
non_zero_cols = 0
# Writing non_zero_rows = sum([any(row) for row in ref_matrix.rowsp]) in a different way
# Iterating through each row in the matrix
for row in ref_matrix.rowsp:
# Checking if the row has any non-zero entries
if any(row):
# Incrementing the non_zero_rows variable
non_zero_rows += 1
# Writing non_zero_cols = sum([any(col) for col in ref_matrix.colsp]) in a different way
# Iterating through each column in the matrix
for col in ref_matrix.colsp:
# Checking if the column has any non-zero entries
if any(col):
# Incrementing the non_zero_cols variable
non_zero_cols += 1

# Checking if the number of non-zero rows > the number of non-zero columns
if non_zero_rows < non_zero_cols:
rank = non_zero_rows
elif non_zero_rows > non_zero_cols: # –> If the number of non-zero rows > the number of non-zero columns
rank = non_zero_cols
else:
rank = non_zero_rows

# Returning the rank of the matrix
return rank
”’
m = Matrix([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
n = Matrix([[1, 3, 5, 9], [1, 3, 1, 7], [4, 3, 9, 7], [5, 2, 0, 9]])
o = Matrix([[1, 2], [3, 4]])
p = Matrix([[-24, 60, 56, -28, 24, 80], [-6, 15, 14, -7, 6, 20], [-36, 20, 24, 36, -8, -34], [-16, 9, -5, -2, -9, 9], [-18, 10, 12, 18, -4, -17]])
q = Matrix([[13, -8, -13, 1, -19, 1, 7], [11, 6, -109, 122, 26, 125, -3], [11, 17, 10, -9, -9, -6, -11], [11, -1, 18, -18, -9, -8, 18], [16, 7, 6, 7, 15, -4, 19], [0, -1, 13, -20, -5, -19, 3], [14, -7, -15, -10, 6, -18, 13]])

print(m.ref())
# Output: [[1, 2, 3], [0, -3, -6], [0, 0, 0]]
print(n.ref())
# Output: [[1, 3, 5, 9], [0, -9, -11, -29], [0, 0, -4, -2], [0, 0, 0, 94/9]]
print(o.ref())
# Output: [[1, 2], [0, -2]]
print(p.ref())
# Output: [[1, 0, 0, 0, 0.638066, -1.64437], [0, 1, 0, 0, 0.3287, -1.74054], [0, 0, 1, 0, 0.3498, 1.33333], [0, 0, 0, 1, 0, -2.510744], [0, 0, 0, 0, 0, 0]]
print(q.ref())
”’
“””RANK TESTER CELL
A = Matrix([[0, 1, 2], [3, 4, 5], [6, 7, 8]])
print(A)
print(“Rank:”, A.rank(), “\nExpected: 2\n”)

B = Matrix([[1, 2], [-1, -2]])
print(B)
print(“Rank:”, B.rank(), “\nExpected: 1\n”)

C = Matrix([[0, -1, 5], [2, 4, -6], [1, 1, 5]])
print(C)
print(“Rank:”, C.rank(), “\nExpected: 3\n”)

D = Matrix([[5, 3, 0], [1, 2, -4], [-2, -4, 8]])
print(D)
print(“Rank:”, D.rank(), “\nExpected: 2\n”)

E = Matrix([[1, 2, -1, 3], [2, 4, 1, -2], [3, 6, 3, -7]])
print(E)
print(“Rank:”, E.rank(), “\nExpected: 2”)
“””
Problem 2
Implement the function gauss_solve(A, b) that solves the system  Ax→=b→
. The input A is of the type Matrix and b is of the type Vec.

If the system has a unique solution, it returns the solution as a Vec object.
If the system has no solution, it returns None.
If the system has infinitely many solutions, it returns the number of free variables (int) in the solution.
# Writing the gauss_solve(A, b) function to solve the system of linear equations
def gauss_solve(A, b):
# TODO: Constructing a new matrix by appending the b vector to the A matrix
aug_matrix = []
# Converting the augmented matrix into a Matrix object
aug_matrix = Matrix(aug_matrix)
# Converting the augmented matrix into reduced row echelon form
ref_aug_matrix = aug_matrix.ref()
# Storing the number of columns of the reduced, augmented matrix
aug_mat_cols = len(ref_aug_matrix.col_space())

# Checking if the system of equations has no, one or infinite solutions
if A.rank() < ref_aug_matrix.rank():
return None
elif A.rank() == ref_aug_matrix.rank() == aug_mat_cols:
result = []
# TODO: Using back substitution to solve the system of equations
return Vec(result)
elif A.rank() < aug_mat_cols and ref_aug_matrix.rank() < aug_mat_cols:
free_variables = aug_mat_cols – A.rank()
return free_variables
“””TESTER CELL #1 FOR GAUSSIAN ELIMINATION”””
A = Matrix([[0, 1, 2], [3, 4, 5], [6, 7, 8]])
b = Vec([9, 10, 11])
sol = gauss_solve(A, b)
print(“Result:”, sol)
print(“Expected: 1”)
“””TESTER CELL #2 FOR GAUSSIAN ELIMINATION
A = Matrix([[1, 0, 5], [0, 1, 2], [3, 2, 0]])
b = Vec([6, 3, 5])
sol = gauss_solve(A, b)
print(“Returned:”, sol)
print(“Expected: [1.0, 1.0, 1.0]”)
“””
Returned: None
Expected: [1.0, 1.0, 1.0]
“””TESTER CELL #3 FOR GAUSSIAN ELIMINATION
A = Matrix([[1, 1, 5], [2, 2, 10]])
b = Vec([6, 3])
sol = gauss_solve(A, b)
print(“Returned:”, sol)
print(“Expected: None”)
“””
Problem 3
Implement the function is_independent(S) that returns True if the set S of Vec objects is linearly independent, otherwise returns False.

# Writing a function that returns true/false based on whether
# the given set of vectors is linearly independent or not
def is_independent(S):
# Two arrays for storing the matrix and vector
A = []
B = []
# Iterating through the vector space
for x in S:
# Storing the elements of the matrix
A_new = []
# Iterating through the elements of the vector
for y in range(len(x.elements)):
# Appending the elements of the vector to the matrix
A_new.append(x.elements[y])
# Appending the elements of the vector to the matrix
B.append(0)
# Appending the matrix to the list
A.append(A_new)

# Converting the matrix and vector into Matrix and Vec objects
A_matrix = Matrix(A)
B_vector = Vec(B)

# Running the gauss_solve() function to solve the system of linear equations
gauss_solution = gauss_solve(A_matrix, B_vector)

# Checking if the system of linear equations has no solution
if type(gauss_solution) == Vec:
# Iterating through the elements of the vector
for i in gauss_solution.elements:
# Checking if the element is not zero
if i != 0:
break
# Returning true, indicating that the vectors are linearly independent
return True
# Returning false, indicating that the vectors are linearly dependent
return False
“””IS-INDEPENDENT TESTER CELL

S1 = {Vec([1, 2]), Vec([2, 3]), Vec([3, 4])}

print(“S1 is Independent:”, is_independent(S1))
print(“Expected: False”)

S2 = {Vec([1, 1, 1]), Vec([1, 2, 3]), Vec([1, 3, 6])}

print(“S2 is Independent:”, is_independent(S2))
print(“Expected: True”)
“””
Problem 4
Implement the function gram_schmidt(S) that applies the Gram-Schmidt process to create an orthonormal set of vectors from the vectors in S. The function raises a ValueError if the set S is NOT linearly independent.

INPUT:

S a set of Vec objects
OUTPUT:

a set of Vec objects representing orthonormal vectors.
HINT:

If  S={x1→,x2→,…,xn−→}
is a set of linearly independent vectors, then Gram-Schmidt process returns the set  {u1→,u2→,…,un−→}
where,

ui→=1||wi−→||2wi−→
for  i=1,2,…n
,
and

w1−→=x1→

wi−→=xi→−∑i−1j=1projwj−→(xi→)
for  i=2,3,…n

# Writing a function that returns the orthonormal set of vectors in S
def gram_schmidt(S):
if is_independent(S) == False:
raise ValueError(“The vectors in S are not linearly independent.”)
else:
None
pass
“””TESTER CELL #1 FOR GRAM SCHMIDT
S = {Vec(1, -1), Vec(0, 2)}
T = gram_schmidt(S)

str_T = “{”
for v in T:
str_T += str(v) + ‘T ‘
str_T += “}”

print(strT)
print(“Expected: {[0.707106, -0.707106]T, [0.707106, 0.707106]T}”)
“””
“””TESTER CELL #2 FOR GRAM SCHMIDT
S = {Vec(1, -2), Vec(-4, 8)}
try:
T = gram_schmidt(S)
print(“INCORRECT: ValueError was not raised.”)
except ValueError:
print(“CORRECT: ValueError was raised.”)
except:
error = traceback.format_exc()
print(“INCORRECT: The following unexpected error occurred:\n\n” + str(error))
“””

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