Omit columns averages from a matrix.

For example: A =

    16     2     3    13
     5    11    10     8
     9     7     6    12
     4    14    15     1

mean_of_each_column = 8.5000 8.5000 8.5000 8.5000

Result=

     7.5000   -6.5000   -5.5000    4.5000

    -3.5000    2.5000    1.5000   -0.5000

     0.5000   -1.5000   -2.5000    3.5000

    -4.5000    5.5000    6.5000   -7.5000