# Examples of memory aliasing

**URL:** <https://discourse.julialang.org/t/examples-of-memory-aliasing/50382>\
**Category:** General Usage\
**Tags:** aliasing\
**Created:** [November 18, 2020, 2:59pm UTC](https://discourse.julialang.org/t/examples-of-memory-aliasing/50382 "2020-11-18T14:59:34Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![wulpuqu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/wulpuqu/32/17640_2.png) [@wulpuqu](https://discourse.julialang.org/u/wulpuqu)\
**Post date:** [November 18, 2020, 2:59pm UTC](https://discourse.julialang.org/t/examples-of-memory-aliasing/50382/1 "2020-11-18T14:59:34Z")

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Hello,

I was reading the definition of `AbstractArray` in `Base` and I was searching for concrete cases of memory aliasing with two `AbstractArrays`.

A simple case with SubArrays.

```julia
julia> A=randn(10)

julia> Base.mightalias(A,view(A,1:5))
true

```

Do you know other examples in `Base` without using SubArrays ?

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<div class="post-metadata">

**Author:** ![rdeits](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/rdeits/32/286_2.png) [@rdeits](https://discourse.julialang.org/u/rdeits)\
**Post date:** [November 18, 2020, 3:07pm UTC](https://discourse.julialang.org/t/examples-of-memory-aliasing/50382/2 "2020-11-18T15:07:50Z")

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Two examples that come to mind are reshaping and transposing:

```julia
julia> A = rand(3, 3);

julia> Base.mightalias(A, vec(A))
true

julia> Base.mightalias(A, reshape(A, :))
true

julia> Base.mightalias(A, transpose(A))
true

```

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<div class="post-metadata">

**Author:** ![wulpuqu](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/wulpuqu/32/17640_2.png) [@wulpuqu](https://discourse.julialang.org/u/wulpuqu)\
**Post date:** [November 18, 2020, 3:14pm UTC](https://discourse.julialang.org/t/examples-of-memory-aliasing/50382/3 "2020-11-18T15:14:35Z")

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Nice ! I forgot that reshaping was actually not allocating a new chunk of memory !