Question

A=[-6,8,2;1,-3,20;15,-10,5];

Write a program that computes the array B by computing the natural logarithm of all the elements of A whose value is greater than or equal to 1. Otherwise add 30 to each element that is less than 1. Do this in two way.

A) By using a for loop with conditional statements

B)By using a logical array as a mask

MATLAB CODE

Answer 1

Matlab:

A = [-6 8 2;1 -3 20;15 -10 5];

A(A<1) = A(A<1)+30;

B = log(A);

disp('using conditional mask');

disp(B);

A = [-6 8 2;1 -3 20;15 -10 5];

for i=1:3

for j=1:3

if A(i,j)<1

A(i,j) = A(i,j)+30;

end

end

end

B = log(A);

disp('using for loop');

disp(B);

command window log:

using conditional mask

3.1781 2.0794 0.6931

0 3.2958 2.9957

2.7081 2.9957 1.6094

using for loop

3.1781 2.0794 0.6931

0 3.2958 2.9957

2.7081 2.9957 1.6094

>>