Substraction with sum / loop

Hello everybody !

I have a vector A and a matrix B

A= [10 20 30] 

B=  2 5  10
    4 10 20
    6 15 30

so if I want to calculate the following matrix : here I want to substract the first elment of the vector to the first column by and then the second element to the second columns and the third element to the third column..by this way :

   C= 10-2       20-5          30-10
      10-2-4     20-5-10       30-10-20
      10-2-4-6   20-5-10-15    30-10-20-30

So as shown, I want to substract the first element of the vector to the first column elements , substract the first element, keep result then substract to the second element, keep result, substract to the third element .. Thank you

Answer 1

[Jan]

I assume that the FOR loop is not essential.

Result = A - cumsum(B, 1);  % Matlab 2016b autoexpanding

For older Matlab versions:

Result = bsxfun(@minus, A, cumsum(B, 1));

[heir ancestors]

Hello Jan thank you very much ;

The code is working great ! Just in my case it's

Result=bsxfun(@minus,A',cumsum(B,1));

[Jan]

You are welcome. I love Matlab for this compact coding. This would be a small battle in C!   :-(

[heir ancestors]

oh yes :D , thank you again :)