delete and insert entries in a vector

Hi All,

I have the following vector

c = [1 1 3 4 5 6 7 8 11 10]

I have to delete entries in position 2 and 9

c_idx = 1:length(c)

c = c(c_idx(c_idx ~=2 & c_idx~=9))

gives,

c_tilda = [ 1 3 4 5 6 7 8 10]

Using c_tilda, I perform a matrix operation

x = A*c_tilda

say, the resulting x is

x = [0.1 0.3 0.4 0.05 0.6 0.7 0.8 0.1]

Now, I'd like to insert values in position 2 and 9 of c in x .

Expected x = [0.1 1 0.3 0.4 0.05 0.6 0.7 0.8 11 0.1]

Could someone suggest how this can be done?

[Walter Roberson]

What happened to the second 0.1 in x? You got rid of the second 0.1 and inserted three new values, 1 11 10

[Deepa Maheshvare]

Thanks a lot for the repsonse. Please check the edit.

Answer 1

[Fabio Freschi]

If A is a matrix, I assume you have column vectors, if not, please provide A

% your (column) vector
c = [1 1 3 4 5 6 7 8 11 10].';

iRemove = [2; 9];
iKeep = setdiff(1:length(c),iRemove);

% dummy A
A = rand(length(iKeep));

% your calculation
xReduced = A*c(iKeep);

% preallocation of x
x = zeros(size(c));

% set complete x vector
x(iKeep) = xReduced;
x(iRemove) = c(iRemove);