how to find difference between column elemnts in a matrix ?

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aditya sahu on 13 Jun 2017
Edited: Stephen on 14 Jun 2017
Let my matrix is
3 2 14 5
7 1 8 9
11 11 12 13
I need to find the substraction between column 1 and 2 and store the result in coulmn 1. similarily for coulmn 3 and 4 and result will be in coulmn 2. i.e the result should be like this
1 9
6 -1
0 -1
kindly, suggest solution. Thank you.

Stephen on 13 Jun 2017
Edited: Stephen on 14 Jun 2017
A general solution (without hard-coded columns):
>> M(:,1:2:end) - M(:,2:2:end)
ans =
1 9
6 -1
0 -1
EDIT: if you have uint8 image data, then convert to double first:
double(M(:,1:2:end)) - double(M(:,2:2:end))
aditya sahu on 14 Jun 2017
Thank you @walter-roberson and @Stephen Cobeldick ,,i got it...my matrix was actually uint8 and i am expacting negative, sorry for my mistake..but thank you for your suggestion...

Walter Roberson on 13 Jun 2017
Result = YourMatrix(:,[1 3]) - YourMatrix(:,[2 4])
aditya sahu on 13 Jun 2017
Thank you, but suppose my matrix is 512*512 size then how to do?