# LinearMaps and ITensors incompatibility? **URL:** \ **Category:** ITensor Development\ **Created:** [January 28, 2025, 1:24am UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216 "2025-01-28T01:24:37Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![srwhite](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@srwhite](https://itensor.discourse.group/u/srwhite)\ **Post date:** [January 28, 2025, 1:24am UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/1 "2025-01-28T01:24:37Z")
I am encountering strange incompatibility between LinearMaps and ITensors. I have LinearMaps v3.11.3 and ITensors v0.7.11. “using” hangs when I try to do both: faraday% julia \_ \_ \_ _(_)\_ | Documentation: [https://docs.julialang.org](https://docs.julialang.org) (_) | (_) (_) | \_ \_ | | \_\_ \_ | Type “?” for help, “]?” for Pkg help. | | | | | | |/ ` | | | | || | | | (_| | | Version 1.11.3 (2025-01-21) _/ |\ __‘_|_|_|\__ ’\_| | Official [https://julialang.org/](https://julialang.org/) release |\_\_/ | julia\> using LinearMaps julia\> faraday% julia \_ \_ \_ _(_)\_ | Documentation: [https://docs.julialang.org](https://docs.julialang.org) (_) | (_) (_) | \_ \_ | | \_\_ \_ | Type “?” for help, “]?” for Pkg help. | | | | | | |/ ` | | | | || | | | (_| | | Version 1.11.3 (2025-01-21) _/ |\ __‘_|_|_|\__ ’\_| | Official [https://julialang.org/](https://julialang.org/) release |\_\_/ | julia\> using ITensors julia\> faraday% julia \_ \_ \_ _(_)\_ | Documentation: [https://docs.julialang.org](https://docs.julialang.org) (_) | (_) (_) | \_ \_ | | \_\_ \_ | Type “?” for help, “]?” for Pkg help. | | | | | | |/ ` | | | | || | | | (_| | | Version 1.11.3 (2025-01-21) _/ |\ __‘_|_|_|\__ ’\_| | Official [https://julialang.org/](https://julialang.org/) release |\_\_/ | julia\> using LinearMaps, ITensors ---
**Author:** ![mtfishman](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/mtfishman/32/11_2.png) [@mtfishman](https://itensor.discourse.group/u/mtfishman)\ **Post date:** [January 28, 2025, 2:57pm UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/2 "2025-01-28T14:57:44Z")
Hi Steve, that is really strange, I’m seeing the same thing. I’ve never seen anything like that, I don’t even know where to start in terms of debugging that… It seems to have something to do with the precompilation step, but I don’t know why that combination of packages is causing issues for that. Have you been able to load both of those packages before with older versions? ---
**Author:** ![srwhite](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@srwhite](https://itensor.discourse.group/u/srwhite)\ **Post date:** [January 28, 2025, 5:41pm UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/3 "2025-01-28T17:41:53Z")
Yes, I’ve had both included with using for years. When I first saw this, I thought it was because my ITensors package was not updating to the most recent version because of dependencies. It was at v0.6 something. So I resolved the dependencies to get the latest versions of both, but the issue was still there. Does ITensors itself use LinearMaps? ---
**Author:** ![mtfishman](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/mtfishman/32/11_2.png) [@mtfishman](https://itensor.discourse.group/u/mtfishman)\ **Post date:** [January 28, 2025, 5:55pm UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/4 "2025-01-28T17:55:57Z")
> [@srwhite](#): > > Does ITensors itself use LinearMaps? It used to at some point, but [not anymore](https://github.com/search?q=repo%3AITensor%2FITensors.jl+LinearMaps&type=code). ---
**Author:** ![mtfishman](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/mtfishman/32/11_2.png) [@mtfishman](https://itensor.discourse.group/u/mtfishman)\ **Post date:** [January 28, 2025, 6:54pm UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/5 "2025-01-28T18:54:44Z")
On my machine in a clean project environment, I see the following: ```julia julia> @time using ITensors, LinearMaps 253.731965 seconds (668.87 M allocations: 26.942 GiB, 0.99% gc time, 0.09% compilation time: 97% of which was recompilation) (jl_UZZAhk) pkg> st Status `/private/var/folders/qz/q22pzwm144z9fq57mpf1hfp40000gq/T/jl_UZZAhk/Project.toml` [9136182c] ITensors v0.7.11 [7a12625a] LinearMaps v3.11.3 julia> versioninfo() Julia Version 1.11.3 Commit d63adeda50d (2025-01-21 19:42 UTC) Build Info: Official https://julialang.org/ release Platform Info: OS: macOS (arm64-apple-darwin24.0.0) CPU: 10 × Apple M1 Max WORD_SIZE: 64 LLVM: libLLVM-16.0.6 (ORCJIT, apple-m1) Threads: 1 default, 0 interactive, 1 GC (on 8 virtual cores) ``` So they load eventually, but it takes over 4 minutes and it involves allocating an insane amount of memory. Loading them separately is fine: ```julia julia> @time using ITensors 1.413191 seconds (2.45 M allocations: 193.174 MiB, 4.16% gc time, 14.81% compilation time: 97% of which was recompilation) (jl_EKzBab) pkg> st Status `/private/var/folders/qz/q22pzwm144z9fq57mpf1hfp40000gq/T/jl_EKzBab/Project.toml` [9136182c] ITensors v0.7.11 ``` and: ```julia julia> @time using LinearMaps 0.009610 seconds (11.16 k allocations: 865.648 KiB) (jl_7QvL25) pkg> st Status `/private/var/folders/qz/q22pzwm144z9fq57mpf1hfp40000gq/T/jl_7QvL25/Project.toml` [7a12625a] LinearMaps v3.11.3 ``` Definitely something very strange going on. ---
**Author:** ![mtfishman](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/mtfishman/32/11_2.png) [@mtfishman](https://itensor.discourse.group/u/mtfishman)\ **Post date:** [January 31, 2025, 7:21pm UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/6 "2025-01-31T19:21:15Z")
It looks like [[WIP] [NDTensors] Excise libraries by mtfishman · Pull Request #1601 · ITensor/ITensors.jl · GitHub](https://github.com/ITensor/ITensors.jl/pull/1601) will fix this compilation issue. When I use the versions of NDTensors.jl and ITensors.jl on that branch I see: ```julia julia> @time using ITensors, LinearMaps Precompiling ITensors... 3 dependencies successfully precompiled in 7 seconds. 117 already precompiled. 8.408726 seconds (2.46 M allocations: 171.095 MiB, 0.40% gc time, 3.05% compilation time: 90% of which was recompilation) ``` We have to wait a few days to merge that since it relies on registering a new dependent package ([New package: TypeParameterAccessors v0.2.2 by JuliaRegistrator · Pull Request #124121 · JuliaRegistries/General · GitHub](https://github.com/JuliaRegistries/General/pull/124121)), which has a mandatory 3 day waiting period. ---
**Author:** ![mtfishman](https://yyz2.discourse-cdn.com/free1/user_avatar/itensor.discourse.group/mtfishman/32/11_2.png) [@mtfishman](https://itensor.discourse.group/u/mtfishman)\ **Post date:** [February 4, 2025, 4:18am UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/7 "2025-02-04T04:18:47Z")
@srwhite this issue should be fixed with the latest ITensors.jl v0.8 release: ```julia julia> @time using LinearMaps, ITensors 0.955740 seconds (1.36 M allocations: 80.760 MiB, 32.83% compilation time: 97% of which was recompilation) (jl_SZhGpa) pkg> st Status `/private/var/folders/qz/q22pzwm144z9fq57mpf1hfp40000gq/T/jl_SZhGpa/Project.toml` [9136182c] ITensors v0.8.0 [7a12625a] LinearMaps v3.11.3 ``` ---
**Author:** ![srwhite](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@srwhite](https://itensor.discourse.group/u/srwhite)\ **Post date:** [February 7, 2025, 4:05pm UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/8 "2025-02-07T16:05:41Z")
Fantastic! Thanks! ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/itensor/original/1X/d3072b13e047cd06df7f3981547c0917d940dfa4.png) [@system](https://itensor.discourse.group/u/system)\ **Post date:** [February 17, 2025, 4:06pm UTC](https://itensor.discourse.group/t/linearmaps-and-itensors-incompatibility/2216/9 "2025-02-17T16:06:43Z")
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