MATLAB: How to change a sign of elements in a matrix for each coulmn separatly

MATLAB

I want to change

v = [-2 3 0.5 4 22 15 -19 -0.01 104 78]

vny = [-2 -3 0.5 -4 22 -15 -19 0.01 104 -78]

thanks for tips

Best Answer

vny = v;
vny( 2:2:end) = -vny( 2:2:end);

should work

Related Solutions

MATLAB: Choose n out of every 4 elements randomly.

Try this:

% Create sample data.
m = randi(9, 1, 124);
% Define how many from each block of 4 you want to take
n = 3;
% Reshape m to have 4 columns and 31 rows
mReshaped = reshape(m, [], 4);
[rows, columns] = size(mReshaped);
% Preallocate an output array
out = zeros(rows, n);
for row = 1 : size(mReshaped, 1)
  % Get random column indexes.
  randomColumns = randperm(4, n)
  % Extract those elements into our output matrix.
  out(row,:) = mReshaped(row,randomColumns);
end
out % Print to command window.

MATLAB: Multiplying every secound element in a vector with -1

You need to start learning MATLAB. That is, actually learn to use vectors, matrices, not just work with single numbers, and loops. Until you do, you will continue to have these problems.

Here is one way to do what you asked for. There are surely a zillion others.

v = 1:10;
vny = v.*(mod(1:numel(v),2)*2 - 1)
vny =
     1    -2     3    -4     5    -6     7    -8     9   -10

The point is to start thinking in terms of a vector and vector operations, tools that operate on every element of a vector in one call.

Best Answer

Related Solutions

MATLAB: Choose n out of every 4 elements randomly.

MATLAB: Multiplying every secound element in a vector with -1

Related Question