# Questions related to -0.0 and 0.0
**URL:** https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158
**Category:** General Usage
**Tags:** question
**Created:** [October 21, 2021, 2:55pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158 "2021-10-21T14:55:11Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@leon](https://discourse.julialang.org/u/leon)
#### Post date: [October 21, 2021, 2:55pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/1 "2021-10-21T14:55:11Z")
I’m using PCHIPInterpolation to do some interpolation.
`itp = Interpolator(xs, ys);`
This program absolutely does not allow any values in its x to be duplicates. I now have some values like the below in my data sets:
`xs = [-5.0, -0.0, 0.0, 10.0, 19.0];`
The interpolation would stop and give an error: “xs must be stricly increasing”. I tried to fix this issue by first using the unique function, but unique actually think they are different.
Is there a better way to address this issue?
---
### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [October 21, 2021, 2:56pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/2 "2021-10-21T14:56:41Z")
See [Is this a bug of the Julia function "unique"? - #30 by giordano](https://discourse.julialang.org/t/is-this-a-bug-of-the-julia-function-unique/70141/30) The next patch release of 1.6, and 1.7.0 will both fix this.
TLDR is that `unique` currently and incorrectly uses `==` instead of `isequal`
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### Author:  [@leon](https://discourse.julialang.org/u/leon)
#### Post date: [October 21, 2021, 2:58pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/3 "2021-10-21T14:58:44Z")
Thanks, Oscar. I started the other thread too 🙂
I’m just hoping to find an alternative solution to address the issue, so that I don’t have to wait for the next version of Julia before I can process my data.
For the NaN issue. I have decided to fill it up with some identical numerical values to get it working.
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### Author:  [@Oscar\_Smith](https://discourse.julialang.org/u/Oscar_Smith)
#### Post date: [October 21, 2021, 3:03pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/4 "2021-10-21T15:03:58Z")
you could always perform minor type piracy and redefine `Base.unique` to do the thing it will do as of the next release. It’s not a great solution, but it will work.
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### Author:  [@GunnarFarneback](https://discourse.julialang.org/u/GunnarFarneback)
#### Post date: [October 21, 2021, 3:04pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/5 "2021-10-21T15:04:55Z")
julia\> xs = [-5.0, -0.0, 0.0, 10.0, 19.0];
julia\> unique(t → t == 0 ? 0.0 : t, xs)
4-element Vector{Float64}:
-5.0
-0.0
10.0
19.0
---
### Author:  [@leon](https://discourse.julialang.org/u/leon)
#### Post date: [October 21, 2021, 3:08pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/6 "2021-10-21T15:08:15Z")
Thanks. Unfortunately, I got the below error when testing:
```julia
UndefVarError: t not defined
Stacktrace:
[1] top-level scope
@ In[129]:3
[2] eval
@ ./boot.jl:360 [inlined]
[3] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)
@ Base ./loading.jl:1116
```
> [@GunnarFarneback](#):
>
> xs = [-5.0, -0.0, 0.0, 10.0, 19.0];
>
> julia\> unique(t → t == 0 ? 0.0 : t, xs)
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### Author:  [@nilshg](https://discourse.julialang.org/u/nilshg)
#### Post date: [October 21, 2021, 3:09pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/7 "2021-10-21T15:09:41Z")
No need to wait, you can just use the 1.7 release candidate
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### Author:  [@GunnarFarneback](https://discourse.julialang.org/u/GunnarFarneback)
#### Post date: [October 21, 2021, 3:11pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/8 "2021-10-21T15:11:09Z")
> [@GunnarFarneback](#):
>
> julia\> unique(t → t == 0 ? 0.0 : t, xs)
I think the JuliaMono font fooled my copy and paste. That arrow really should be `->`.
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### Author:  [@sijo](https://discourse.julialang.org/u/sijo)
#### Post date: [October 21, 2021, 3:21pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/9 "2021-10-21T15:21:17Z")
> [@Oscar\_Smith](#):
>
> See [Is this a bug of the Julia function “unique”? - #29 by leon](https://discourse.julialang.org/t/is-this-a-bug-of-the-julia-function-unique/70141/30) The next patch release of 1.6, and 1.7.0 will both fix this.
>
> TLDR is that `unique` currently and incorrectly uses `==` instead of `isequal`
I don’t think that will solve @leon’s problem? Since `isequal(0.0, -0.0) == false` the values returned by `unique` will still include 0.0 and -0.0…
Actually if `unique` is currently using `==` I don’t understand why both are included in the result, since
```julia
julia> 0.0 == -0.0
true
```
---
### Author:  [@leon](https://discourse.julialang.org/u/leon)
#### Post date: [October 21, 2021, 3:53pm UTC](https://discourse.julialang.org/t/questions-related-to-0-0-and-0-0/70158/10 "2021-10-21T15:53:48Z")
It is working now! Thank you so much.
BTW, is there a way I can find the index of the elements that remained? I have another set of data y that goes with the x.
Ind = …
y = y[Ind];
> [@GunnarFarneback](#):
>
> unique(t → t == 0 ? 0.0 : t, xs)