elimination of the chosen elements and rearranging the matrix

a=[1 2 3 4 5 6 7 8 nan nan nan nan nan];
for i=1:length(a)
   b(i)=a(i)+1;
   if b(i)< 4 
       b(i)=[];
   elseif b(i)>6
       b(i)=[];
   end
      
end

it gives ans:

a =

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

>> b

b =

0 0 4 5 6 0 0 0 NaN NaN NaN NaN NaN

well, i want to eliminate the elements instead of replacing it by zeros as:

4 5 6 nan nan nan nan nan nan nan nan nan nan

Answer 1

[Guillaume]

Deleting elements of an array while you iterate over elements of an array is never going to work.

In any case, a loop is not needed for what you're doing:

a=[1 2 3 4 5 6 7 8 nan nan nan nan nan];

b = a + 1
b(b < 4 | b > 6) = [];

[Alchemist]

what if the length of 'b' needs to be length of 'a', with remaining elements value as 'nan'