# I want to compare every matrix element to a constant then calculate a new matrix based on every case

2 views (last 30 days)
hamza zoubai on 21 May 2022
Edited: Voss on 21 May 2022
i have a matrix A=[ 1 2 3 4 5 ] and a constant b=3 . and i want to compare each element in that matrix with that constant b and calculate a new matrix based on every case .
if element in A<b then should do A*b
if element in A=>b then should do A+b and i want to calculate a new matrix like this :
C= [ A*b A*b A+b A+b A+b ].

Voss on 21 May 2022
Edited: Voss on 21 May 2022
Use logical indexing:
A = [ 1 2 3 4 5 ];
b = 3;
C = zeros(size(A));
C(A < b) = A(A < b)*b;
C(A >= b) = A(A >= b)+b;
disp(C);
3 6 6 7 8
(Or perhaps more clearly:)
C = zeros(size(A));
idx = A < b; % storing the logical index
C(idx) = A(idx)*b;
C(~idx) = A(~idx)+b;
disp(C);
3 6 6 7 8
##### 2 CommentsShowHide 1 older comment
Voss on 21 May 2022
You're welcome!

R2022a

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!