# Complex number, abs() and IntervalArithmetic

**URL:** https://discourse.julialang.org/t/complex-number-abs-and-intervalarithmetic/18268
**Category:** General Usage
**Created:** [December 4, 2018, 7:45am UTC](https://discourse.julialang.org/t/complex-number-abs-and-intervalarithmetic/18268 "2018-12-04T07:45:54Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![OlivierHnt](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/olivierhnt/32/6227_2.png) [@OlivierHnt](https://discourse.julialang.org/u/OlivierHnt)
#### Post date: [December 4, 2018, 7:45am UTC](https://discourse.julialang.org/t/complex-number-abs-and-intervalarithmetic/18268/1 "2018-12-04T07:45:54Z")

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Good evening,

I ran into an issue in my code earlier with IntervalArithmetic:

```julia
julia> abs.([0..0.01] + [0..1]*im)
1-element Array{Interval{Float64},1}:
 [0, ∞]

julia> norm([0..0.01] + [0..1]*im, 1)
 [0, ∞]

```

However, there is no issue if I use `abs2()`:

```julia
julia> abs2.([0..0.01] + [0..1]*im)
1-element Array{Interval{Float64},1}:
 [0, 1.00011]

```

I did not see anything on the Issue section of IntervalArithmetic.jl but perhaps I am missing something ?  
Should `norm` be avoided when using IntervalArithmetic ?

---

<div class="post-metadata">

### Author: ![dpsanders](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dpsanders/32/3573_2.png) [@dpsanders](https://discourse.julialang.org/u/dpsanders)
#### Post date: [December 4, 2018, 11:54pm UTC](https://discourse.julialang.org/t/complex-number-abs-and-intervalarithmetic/18268/2 "2018-12-04T23:54:30Z")

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Cross-ref for tracking the issue: [https://github.com/JuliaIntervals/IntervalArithmetic.jl/issues/245](https://github.com/JuliaIntervals/IntervalArithmetic.jl/issues/245)