Adding the first row of a matrix to every row

Hello,

Question asks to Create a matrix A of 'm'x'n' defined by: A(i,j)=ij+i if i is odd, and A(i,j)=i+jif i is even.

I've got that in the bag but there is a operation step that I'm not having any luck with. "Add the first row to every row other than the first row" My presumption was using the operation A(i,:) = A(i,:) - A(1,:) however the problem that I'm coming across is that testing any values of m and n above 2 would lead to only the last row being operated on. is that line of code inappropriate for the operation?

[Jan]

@amy wang: A confusing question.

 Add the first row to every row

Sounds like a job for the operator "+", but you use "-".

 testing any values of m and n above 2 would lead to only the
 last row being operated on

It seems like there is a problem in your code, but you do not post it. Then guessing the reason is hard.

What is the relation between

 A(i,j)=ij+i if i is odd, and A(i,j)=i+j if i is even

and

 Add the first row to every other row

?

Answer 1

[KSSV]

Many methods are possible, one of the way:

A = rand(3,3) ;
iwant = A+A(1,:) ;  % Add first row to all the rows 
iwant(1,:) = A(1,:) ; % Replace the first row of result with first row of A

Answer 2

[Jan]

A         = rand(3, 4);
A(2:3, :) = A(2:3, :) + A(1, :);   % Auto-expand since R2016b

For older versions:

A(2:3, :) = bsxfun(@plus, A(2:3, :), A(1, :));