# Bug in algebra in REPL?

**URL:** <https://discourse.julialang.org/t/bug-in-algebra-in-repl/96500>\
**Category:** General Usage\
**Created:** [March 23, 2023, 11:12am UTC](https://discourse.julialang.org/t/bug-in-algebra-in-repl/96500 "2023-03-23T11:12:59Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Ron\_Backal](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ron_backal/32/44361_2.png) [@Ron\_Backal](https://discourse.julialang.org/u/Ron_Backal)\
**Post date:** [March 23, 2023, 11:12am UTC](https://discourse.julialang.org/t/bug-in-algebra-in-repl/96500/1 "2023-03-23T11:12:59Z")

</div>

I got a very absurd result when I used the REPL today for linear algebra calculations. I entered first the Windows Terminal(new version) and then typed Julia and entered the REPL.  
I calculated some 2 dimensional vector, in a few different ways to verify my computation.  
Then something weird happened. I typed 50\*38 - 41^2 and I got the same two dimensional vector. and then 1900-1681 and got this 2 dimensional vector again. Maybe I defined some weird thing? is it possible to define 1900-1681 = [3;-2]??  
I post my screenshot here.

 ![weird_bug](https://global.discourse-cdn.com/julialang/original/3X/8/1/81fcd9cf6644e516cfbd6e9fa95cbb26319ec420.jpeg)

---

<div class="post-metadata">

**Author:** ![nilshg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nilshg/32/2283_2.png) [@nilshg](https://discourse.julialang.org/u/nilshg)\
**Post date:** [March 23, 2023, 11:16am UTC](https://discourse.julialang.org/t/bug-in-algebra-in-repl/96500/2 "2023-03-23T11:16:18Z")

</div>

I assume you have overwritten the definition of `-`, something like:

```julia
julia> a - b = [3, -2]
- (generic function with 1 method)

julia> 1900-1681
2-element Vector{Int64}:
  3
 -2

julia> 5 - 2
2-element Vector{Int64}:
  3
 -2

```

Just to be sure, in a fresh session:

```julia
julia> 50 * 38 - 41^2
219

```