what is the simplest way to add two vectors if size is unknown?

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Mr M.
Mr M. 2015-9-16
评论： Steven Lord 2015-9-16
I would like to add v + u. I know v is 1XN but u can be 1xN or Nx1. Is it possible to do without if, and without defining a new variable, for example: w = u(:);

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回答（3 个）

Thorsten
Thorsten 2015-9-16
You can use the colon operator : to convert the 1XN or Nx1 vectors v and u to Nx1 and then add both
x = v(:) + u(:);
Titus Edelhofer
Titus Edelhofer 2015-9-16
Hi,
if you know that v is a row:
x = v + u(:)';
Titus
Steven Lord
Steven Lord 2015-9-16
v = 1:10;
u = v.^2;
if rand > 0.5
u = u.';
end
At this point, we can't be sure of the orientation of u. Let's force u to be the same orientation as v.
w = v + reshape(u, size(v));
  2 个评论
Mr M.
Mr M. 2015-9-16
sorry, i didnt describe the problem fully, in my case I would like to add: u(10:20) + v(30:40) and I dont know the size of v (coud be 1x10 or 10x1)
Steven Lord
Steven Lord 2015-9-16
There's no such thing as the 30th element of a vector with 10 elements, so with either of your v vector orientations v(30) will error.

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