Answer:
Complete Matalb code along with explanation and output results are given below
Explanation:
We are given following two matrices A and B of size 4x3
A = [1 4 2; 2 4 100; 7 9 7; 3 pi 42]
B = log(A)
(a) Select just the second row of B
% to extract any row use this syntax B(row no, : ) we can also extract more than 1 row or any particular elements in a specific row
B_row_2 = B(2,:)
(b) Evaluate the sum of the second row of B
% simply use the sum function and pass it any vector or matrix and it will return their sum
sum_B_row_2 = sum( B_row_2(:) )
(c) Multiply the second column of B and the first column of A element by element
% first we extract the column 2 of matrix B and column 1 of matrix A. use this syntax B( : ,col no ) to extract any column
B_col_2 = B(:,2)
A_col_1 = A(:,1)
% Then we use ( .*) to multiply element by element. To use standard multiplication of matrices only use asterisk sign without coma
multiply=B_col_2.*A_col_1
(d) Evaluate the maximum value in the vector resulting from element-by- element multiplication of the second column of B with the first column of A
% we can find the maximum value in a vector or matrix by using max function so we pass the multiply variable where our result was stored
max_value = max(multiply)
(e) Use element-by-element division to divide the first row of A by the first three elements of the third column of B. Evaluate the sum of the elements of the resulting vector
% First we extract the row 1 of matrix A
A_row_1 = A(1,:)
% Then we extract the column 3 of matrix B
B_col_3 = B(:,3)
% Then we extract the first 3 elements of column 3 of matrix B
B_col_3 = B_col_3(1:3)
% Finally we use ( ./ ) to use element by element division
divide = A_row_1./B_col_3
% Using the sum function again results in the addition of entire elements of resultant matrix
sum_divide = sum( divide(:) )
Only Code:
A = [1 4 2; 2 4 100; 7 9 7; 3 pi 42]
B = log(A)
B_row_2 = B(2,:)
sum_B_row_2 = sum( B_row_2(:) )
B_col_2 = B(:,2)
A_col_1 = A(:,1)
multiply=B_col_2.*A_col_1
max_value = max(multiply)
A_row_1 = A(1,:)
B_col_3 = B(:,3)
B_col_3 = B_col_3(1:3)
divide = A_row_1./B_col_3
sum_divide = sum( divide(:) )
Output Results:
A =
1.0000 4.0000 2.0000
2.0000 4.0000 100.0000
7.0000 9.0000 7.0000
3.0000 3.1416 42.0000
B =
0.00000 1.38629 0.69315
0.69315 1.38629 4.60517
1.94591 2.19722 1.94591
1.09861 1.14473 3.73767
B_row_2 = 0.69315 1.38629 4.60517
sum_B_row_2 = 6.6846
B_col_2 =
1.3863
1.3863
2.1972
1.1447
A_col_1 =
1
2
7
3
multiply =
1.3863
2.7726
15.3806
3.4342
max_value = 15.381
A_row_1 = 1 4 2
B_col_3 =
0.69315
4.60517
1.94591
3.73767
B_col_3 =
0.69315
4.60517
1.94591
divide =
1.44270 5.77078 2.88539
0.21715 0.86859 0.43429
0.51390 2.05559 1.02780
sum_divide = 15.216
