MATLAB: I’ve got a matrix with 4 columns and I want to insert a fifth one and I want it to have either -1,1 or 0 depending on the results of the subtraction of the values from the colums 3 and 2.

Question

354.0000    0.8058    0.0745   -0.7312
356.0000    0.8077    0.2874   -0.5203
358.0000    0.9386    0.2128   -0.7258
360.0000    0.8834    0.1159   -0.7676
362.0000    0.8750    0.2302   -0.6448
364.0000    0.5578    0.0079   -0.5499
366.0000    0.6020    0.4472   -0.1548
368.0000    0.5581    0.3495   -0.2086

For example, I subtracted the values from column 3 and 2 and added the results as a 4th column. Now I want to add a fifth column whose values will be either 1, -1 or 0 depending on the subtraction results of the values from column 3 and 2. I want my 5th column to show 1, when the C3>C2 ; -1 when the C3<C2 and 0 when the C3=C2 and I want to do it for each row in column 5.

Answer 1

x(:,end+1) = double(-(x(:,4) < 0)) + double(x(:,4) > 0);

Because the - converts from logical to double, you do not need the first double; the following also works

x(:,end+1) = -(x(:,4) < 0) + double(x(:,4) > 0);