MATRIX MANUPULATION IF CONDTION NOT WORKING

I have this matrix M:

0 1 2 4

1 5 4 6

3 3 0 1

7 8 0 5

I want to replace the elements in column 4 with 0 corresponding to which elements in column 2 lie between 4 and 9 (in the same row). For example the above matrix should change to :

0 1 2 4

1 5 4 0

3 3 0 1

7 8 0 0

I wrote this code , but it doesen't seem to work .

for i = 1:4
    if 4<M(i,2<9
        M(i,4)=0;
    end
end

[Johan]

Technically the code you wrote can work provided that you divide your logical statement into two combined ones:

M = randi(9,4,4)

M = 4×4

2 4 3 8 5 7 5 4 6 8 6 8 7 5 1 6

M2=M;
for i = 1:4
    if 4<M(i,2) && M(i,2)<9
        M(i,4)=0;
    end
end
M

M = 4×4

2 4 3 8 5 7 5 0 6 8 6 0 7 5 1 0

you can also put a logical matrix in a array variable to change specific data according to your conditions which avoid the need for for loops:

%define value to be changed in colmun 2
conditions = and(M2(:,2)>4,M2(:,2)<9);
%change conditional values in column 4
M2(conditions,4) = 0

M2 = 4×4

2 4 3 8 5 7 5 0 6 8 6 0 7 5 1 0

[SULENDER SAHU]

Thanks for taking the time !!!

Answer 1

[VBBV]

for i = 1:4
  if M(i,2)<9 & M(i,2) >4
      M(i,4)=0;
  end
end

Close the parenthesis and run it.

[SULENDER SAHU]

Thank you very much !!!