# Findn(triu()) in Julia

**URL:** <https://discourse.julialang.org/t/findn-triu-in-julia/87167>\
**Category:** General Usage\
**Created:** [September 12, 2022, 10:42pm UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167 "2022-09-12T22:42:01Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![m\_shah2](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m\_shah2](https://discourse.julialang.org/u/m_shah2)\
**Post date:** [September 12, 2022, 10:42pm UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/1 "2022-09-12T22:42:01Z")

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I am trying to run ai, aj = findn(triu(NA, 1)) and I am getting an error of function not defined

UndefVarError: triu not defined

Stacktrace:  
[1] top-level scope  
@ In[62]:2  
[2] eval  
@ .\boot.jl:368 [inlined]  
[3] include\_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)  
@ Base .\loading.jl:1428

I don’t know if it’s an inbuilt function or has to include using some package. Any help will be appreciated

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<div class="post-metadata">

**Author:** ![jar1](https://avatars.discourse-cdn.com/v4/letter/j/c0e974/32.png) [@jar1](https://discourse.julialang.org/u/jar1)\
**Post date:** [September 12, 2022, 10:47pm UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/2 "2022-09-12T22:47:50Z")

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```julia
julia> using LinearAlgebra

julia> triu
triu (generic function with 11 methods)

```

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<div class="post-metadata">

**Author:** ![m\_shah2](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m\_shah2](https://discourse.julialang.org/u/m_shah2)\
**Post date:** [September 12, 2022, 10:51pm UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/3 "2022-09-12T22:51:43Z")

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Thanks. But now it says findn is not defined. Can you let me know how to find out the function is from which package?

Julia’s error doesn’t give a clear description of the package to be installed.

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<div class="post-metadata">

**Author:** ![m\_shah2](https://avatars.discourse-cdn.com/v4/letter/m/65b543/32.png) [@m\_shah2](https://discourse.julialang.org/u/m_shah2)\
**Post date:** [September 12, 2022, 10:53pm UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/4 "2022-09-12T22:53:56Z")

</div>

UndefVarError: findn not defined

Stacktrace:  
[1] top-level scope  
@ In[69]:1  
[2] eval  
@ .\boot.jl:368 [inlined]  
[3] include\_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)  
@ Base .\loading.jl:1428

---

<div class="post-metadata">

**Author:** ![jar1](https://avatars.discourse-cdn.com/v4/letter/j/c0e974/32.png) [@jar1](https://discourse.julialang.org/u/jar1)\
**Post date:** [September 12, 2022, 10:59pm UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/5 "2022-09-12T22:59:36Z")

</div>

I don’t know about `findn`

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<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:** [September 13, 2022, 5:02am UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/6 "2022-09-13T05:02:32Z")

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I guess the question is where did you find `findn`?

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<div class="post-metadata">

**Author:** ![gustaphe](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/gustaphe/32/18174_2.png) [@gustaphe](https://discourse.julialang.org/u/gustaphe)\
**Post date:** [September 13, 2022, 5:27am UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/7 "2022-09-13T05:27:05Z")

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Consider this: you could string together an enormous number of combinations of letters that could potentially be Julia functions. Which package owns `gldebd()`?

I should only expect that to be an actual function if I’ve implemented it myself or if I’ve read it somewhere, in which case that place should list where they found it.

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<div class="post-metadata">

**Author:** ![digital\_carver](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/digital_carver/32/33818_2.png) [@digital\_carver](https://discourse.julialang.org/u/digital_carver)\
**Post date:** [September 13, 2022, 6:47am UTC](https://discourse.julialang.org/t/findn-triu-in-julia/87167/8 "2022-09-13T06:47:36Z")

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For future readers:

> [@Findn() function not found in Julia](https://discourse.julialang.org/t/findn-function-not-found-in-julia/87175/3):
>
> It looks like findn(A) was a function in quite old versions of Julia, which was [deprecated in Julia 0.7](https://github.com/JuliaLang/julia/pull/25532) in favor of findall(!iszero, A). So, you should update your code to aij = findall(!iszero, triu(NA,1)) where aij is now an array of [CartesianIndex](https://docs.julialang.org/en/v1/base/arrays/#Base.IteratorsMD.CartesianIndex), essentially a kind of multi-component index for indexing multidimensional arrays.