Matlab is summing a row with a column

Hello everyone:

Today I started working with Matlab 2017a and I found what I think is a bug. When I sum [1,2]+[1;2], Matlab is returning [2,3;3,4]. Do you know how to make Matlab warn me when I sum vectors with different dimmensions?

Answer 1

[Image Analyst]

It's not a bug. It's the way the new MATLAB works now. It's called "automatic expansion."

On the release notes: https://www.mathworks.com/help/matlab/release-notes.html

Mathematics Implicit Expansion: Apply element-wise operations and functions to arrays with automatic expansion of dimensions of length 1

Implicit expansion is a generalization of scalar expansion. With scalar expansion, a scalar expands to be the same size as another array to facilitate element-wise operations. With implicit expansion, the element-wise operators and functions listed here can implicitly expand their inputs to be the same size, as long as the arrays have compatible sizes. Two arrays have compatible sizes if, for every dimension, the dimension sizes of the inputs are either the same or one of them is 1. See Compatible Array Sizes for Basic Operations and Array vs. Matrix Operations for more information.

[Gonzalo Benavides]

Thank you so much for the info. Have a great day.

[Image Analyst]

You're welcome. Thanks for accepting.

By the way, the image below explains it pretty well: