Dear folks I’m an old Matlab user who is trying to switch to Julia. In Matlab, I use array (element-wise) arithmetic a lot. When I tried to make element-wise arithmetic using Julia, I noticed the following strange behavior: Adding a scalar to a vector needs dot “.+”, while multiplying them works…

That’s just maths: [image] Why can't you add a scalar to a vector? Why can't you add a scalar to a vector? [image] Multiplication Of Vectors by a Scalar Quantity with examples Multiplication of Vectors can be of two types Scalar and Vector Multip…

[image] ahmed-desoki: Adding a scalar to a vector needs dot “.+”, while multiplying them works fine without the dot!!! Standard linear-algebra operations (e.g. adding/subtracting vectors or other arrays of the same size or multiplying them by scalars, or performing valid matrix/vector multipl…

Thanks for your answer, but please help me understand the rule. Matlab rules are so clear. Why the operation works with addition but fails with multiplication? Why the rule applies to one operator and not on the other??

Welcome to the Julia forum! I feel the Julia rules are clearer (and I also once came from Matlab), because you nearly never “accidentally broadcast” which happened to me in Matlab often and I suddenly hat matrices where I just expected vectors. So maybe to extend on Stevens answer. Assume you have…

I thought that’s what my (and Steven’s) answer had done - when an operation is meaningfully defined mathematically it works, if it isn’t, it doesn’t. As explained in the first link I shared, adding a scalar to a vector is not a well defined operation. Therefore, scalar + vector will aise a method e…

[image] nilshg: I thought that’s what my (and Steven’s) answer had done - when an operation is meaningfully defined mathematically it works, if it isn’t, it doesn’t. As explained in the first link I shared, adding a scalar to a vector is not a well defined operation. I wouldn’t phrase it thi…

[image] ahmed-desoki: Matlab rules are so clear. I’m not so sure about that (Matlab code): >> x = rand(3,1); y = rand(3,1); >> x + y ans = 1.2434 0.7045 1.9281 >> 2 * x ans = 0.5570 1.0938 1.9150 >> 2 + x ans = 2.2785 2.5469 2.9575 These all work. But …

There are some additional answers here you might find useful. [image] Broadcasting inconsistency between addition and multiplication New to Julia There seems to be inconsistency in broadcasting. A = [1 2 ; 3 4] A* 2 # Broadcasting works here A.*2 # Broadcasting same …

Understand vectorized dot operators

New to Julia

Nathan_Boyer March 21, 2023, 3:25pm 9

There are some additional answers here you might find useful.

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Topic		Replies	Views
Broadcasting inconsistency between addition and multiplication New to Julia broadcasting	13	1431	October 8, 2021
Trouble with Dot Syntax: .* Works, .+ and sin. Do Not Work New to Julia question	3	734	November 6, 2020
One element vector cannot be used to multiply another vector/matrix General Usage linearalgebra , arrays	6	1077	November 11, 2021
Array/Vector multiplication for single element arrays New to Julia question	8	10098	May 13, 2020
Vectorized math Performance	12	728	February 17, 2021

Understand vectorized dot operators

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