matrix =[[1, 2, 3],[4, 5, 6]]# Adding a row
matrix.append([7, 8, 9])
for row in matrix:# Adding a column
row.append(0) # Adds a new column with 0 in each row
matrix[0][1] = 20# Change the element in the first row, second column
row_sum = 0# Sum of elements in the first row
for element in matrix[0]:
row_sum += element
def my_function(L, i, j): #return the sum of specific colums
total = 0
if not L or i > j:# Check matrix L is empty or if i > j (invalid range)
return 0
for row in L:# Iterate over each row in the matrix
# Sum the elements from column i to column j (inclusive)
total += sum(row[i:j + 1])
return total # Return the final total sum
def transpose_row_col(M, i, j):# transpose bytte row med columns
M (list of lists): The input square matrix.
i (int): The index of the row to be swapped.
j (int): The index of the column to be swapped.
for k in range(len(M)): # Iterate over all rows/columns
# Swap the elements in row `i` and column `j`
M[i][k], M[k][j] = M[k][j], M[i][k]
# Use a temporary variable to swap the elements in row `i` and column `j`
temp = M[i][k]
M[i][k] = M[k][j]
M[k][j] = temp
return M
def set_upper_triangle(M, val):# forandrer de øverste diagonal med val
for row in range(len(M)): # Iterate through each row
for col in range(row + 1, len(M)): # Target only elements above the diagonal
M[row][col] = val # Replace with the given value
return M # Return the updated matrix
def replace_diagonal(M, i, val):#replaces elements on a diagonal
for row in range(len(M)): # Iterate through each row of the matrix
if i == 0: # If i is 0, target the main diagonal
M[row][row] = val # Replace the element at position [row][row] (main diagonal)
elif i == 1: # If i is 1, target the secondary diagonal
# Replace the element at position [row][len(M) - 1 - row] (secondary diagonal)
M[row][len(M) - 1 - row] = val
return M # Return the modified matrix
