# How to qualify operators like \*, + , etc
**URL:** https://discourse.julialang.org/t/how-to-qualify-operators-like-etc/65220
**Category:** New to Julia
**Tags:** question
**Created:** [July 24, 2021, 7:42am UTC](https://discourse.julialang.org/t/how-to-qualify-operators-like-etc/65220 "2021-07-24T07:42:16Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@viraltux](https://discourse.julialang.org/u/viraltux)
#### Post date: [July 24, 2021, 7:42am UTC](https://discourse.julialang.org/t/how-to-qualify-operators-like-etc/65220/1 "2021-07-24T07:42:17Z")
This should be an easy one, I am trying to run this code
```julia
import Measurements as M
import MonteCarloMeasurements as MCM
using Measurements
using MonteCarloMeasurements
n = 100
x = rand(n,5)
e = rand(n,5)/100
using BenchmarkTools, Statistics
@benchmark cov(x) .- cov(x .M.± e)
@benchmark cov(x) .- cov(x .MCM.± e)
```
and I have this error
`ERROR: syntax: space before "." not allowed in "x ."`
I have tried a few combinations like .M(.±) with no luck. How should we qualify something like `x .± e`?
---
### Author:  [@simeonschaub](https://discourse.julialang.org/u/simeonschaub)
#### Post date: [July 24, 2021, 7:51am UTC](https://discourse.julialang.org/t/how-to-qualify-operators-like-etc/65220/2 "2021-07-24T07:51:22Z")
> [@viraltux](#):
>
> I have tried a few combinations like .M(.±) with no luck. How should we qualify something like `x .± e` ?
`M.:±` should work. You can’t use that as an infix operator though, so you will have to call it as `M.:±.(x, e)`.
---
### Author:  [@viraltux](https://discourse.julialang.org/u/viraltux)
#### Post date: [July 24, 2021, 8:11am UTC](https://discourse.julialang.org/t/how-to-qualify-operators-like-etc/65220/3 "2021-07-24T08:11:43Z")
Great! Thanks @simeonschaub !