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ITensor

20 indexed repositories · View on GitHub

ITensors.jl
A Julia library for efficient tensor computations and tensor network calculations. ITensors.jl is supported by the Simons Foundation's Fl...

Julia · 684 stars
ITensorNetworks.jl
A package with general tools for working with higher-dimensional tensor networks based on ITensor.

Julia · 128 stars
ITensorMPS.jl
MPS and MPO methods based on ITensor (ITensors.jl). ITensorMPS.jl is supported by the Simons Foundation's Flatiron Institute.

Julia · 85 stars
DataGraphs.jl
A simple graph type with data on the vertices and edges.

Julia · 13 stars
NamedGraphs.jl
Extension of `Graphs.jl` to graphs with named vertices.

Julia · 10 stars
ITensorGaussianMPS.jl

Julia · 6 stars
TensorAlgebra.jl

Julia · 3 stars
BlockSparseArrays.jl

Julia · 3 stars
ITensorNetworksNext.jl
A rewrite of ITensorNetworks.jl based on ITensorBase.jl/NamedDimsArrays.jl.

Julia · 3 stars
ITensorRegistry
Local Julia registry for in-progress and unreleased packages

3 stars
ITensorPkgSkeleton.jl
Template for ITensor packages. ITensorPkgSkeleton.jl is supported by the Simons Foundation's Flatiron Institute.

Julia · 1 star
ITensorUnicodePlots.jl

Julia · 1 star
SparseArraysBase.jl
Multidimensional sparse array library. SparseArraysBase.jl is supported by the Simons Foundation's Flatiron Institute.

Julia · 1 star
GaussianFermions.jl
Tools for free fermion calculations

Julia · 0 stars
ITensorVisualizationBase.jl

Julia · 0 stars
TypeParameterAccessors.jl

Julia · 0 stars
ITensorFormatter.jl
Formats to the style used across the ITensor Julia packages.

Julia · 0 stars
ITensorMakie.jl

Julia · 0 stars
ITensorGLMakie.jl

Julia · 0 stars
ITensorBase.jl
A rewrite of ITensors.jl based on NamedDimsArrays.jl.

Julia · 0 stars

Beginner friendly Everything

Open All

[ENHANCEMENT] Add plotting capacity Open

enhancement

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ITensor/NamedGraphs.jl#198 · 1 comment · Opened Sep 10, 2026
index_id_rng() constructs a throwaway Xoshiro() on every call (Index construction ~20× slower than it needs to be) Open

Difficulty 1/5 Under an hour Newbie friendliness 90/100

ITensor/ITensors.jl#1761 · 1 comment · Opened Jul 14, 2026
[BUG] Edge_subgraph fails due to implicitly caring about edge directionality on undirected graphs Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 75/100

ITensor/NamedGraphs.jl#175 · Opened Jul 7, 2026
Implement pre/post processing convenience functions for e.g. `MessageCache` Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ITensor/ITensorNetworksNext.jl#140 · Opened Jun 30, 2026
[NDTensors] [BUG] cuSOLVER SVD silently produces NaN for rectangular rank-deficient matrices on GPU (TDVP) Open

bug NDTensors

Difficulty 4/5 3-5 days Newbie friendliness 48/100

ITensor/ITensors.jl#1753 · Opened May 28, 2026
[ITensors] Support for Reactant Open

enhancement ITensors

Difficulty 5/5 Over a week Newbie friendliness 35/100

ITensor/ITensors.jl#1752 · 1 comment · Opened May 27, 2026
Nested algorithm improvements in `AlgorithmsInterfaceExtensions` Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ITensor/ITensorNetworksNext.jl#113 · Opened May 7, 2026
[NDTensors] [BUG] MethodError: empty(::Bool) in BlockSparseTensor.contract! Open

bug NDTensors

Difficulty 3/5 1-2 days Newbie friendliness 52/100

ITensor/ITensors.jl#1747 · 1 comment · Opened May 7, 2026
Refactor `TensorNetwork` type, and add a reverse index mapping. Open

ITensor/ITensorNetworksNext.jl#111 · 1 assignee · Opened May 6, 2026
ITensorMPS and CUDA.jl Duplication / Erroneous Memory Allocations in DMRG Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ITensor/ITensorMPS.jl#209 · 1 reaction · Opened Apr 22, 2026
Remove `underlying_graph` from the `AbstractDataGraph` interface. Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

ITensor/DataGraphs.jl#104 · Opened Apr 22, 2026
Add `undef` constructor interface for initializing `DataGraph` with undefined data. Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ITensor/DataGraphs.jl#103 · Opened Apr 22, 2026
Add `DatalessView` wrapper to reinterpret a data graph as data-less. Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

ITensor/DataGraphs.jl#102 · 1 reaction · Opened Apr 22, 2026
[ENHANCEMENT] Write subgraphing logic in terms of new function `induced_subgraph_edges`. Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

ITensor/NamedGraphs.jl#152 · 1 reaction · Opened Apr 21, 2026
[BUG] Vector of MPOs in DMRG works for the ground state, but it does not work for the excited states. Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 65/100

ITensor/ITensorMPS.jl#207 · Opened Apr 14, 2026
Add option to print formatted text to `stdout`. Open

enhancement

Difficulty 3/5 1-2 days Newbie friendliness 48/100

ITensor/ITensorFormatter.jl#45 · Opened Mar 10, 2026
[ENHANCEMENT] Make `expect` vertices input consistent Open

enhancement

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ITensor/ITensorNetworks.jl#306 · Opened Mar 8, 2026
Allow creating operators from matrices Open

improvement

ITensor/GaussianFermions.jl#7 · 1 assignee · Opened Mar 6, 2026
Warning when calling `total_density` function Open

bug

ITensor/GaussianFermions.jl#6 · 1 assignee · Opened Mar 4, 2026
Make instantiating the quotient graph of an `AbstractDataGraph` return a `DataGraph` as a fallback. Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ITensor/DataGraphs.jl#91 · Opened Mar 4, 2026
[BUG] write_when_maxdim_exceeds not working for TDVP Open

bug

Difficulty 4/5 3-5 days Newbie friendliness 42/100

ITensor/ITensorMPS.jl#176 · Opened Feb 20, 2026
Typo in definition of "Adagdn" for ElecK site type in the example Open

bug

Difficulty 1/5 Under an hour Newbie friendliness 58/100

ITensor/ITensorMPS.jl#175 · Opened Feb 16, 2026
[ENHANCEMENT] Further improvements to graph indexing code logic Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 20/100

ITensor/NamedGraphs.jl#116 · Opened Jan 30, 2026
[BUG] Broadcasting a vector into an `n x 1` block sparse matrix fails Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 55/100

ITensor/BlockSparseArrays.jl#200 · Opened Jan 16, 2026
[BUG] Block sparse matvec is broken Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 52/100

ITensor/BlockSparseArrays.jl#199 · Opened Jan 16, 2026
[BUG] `*(block sparse, dense)` (and vice versa) is slow Open

bug

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ITensor/BlockSparseArrays.jl#197 · 6 comments · Opened Jan 15, 2026
[ENHANCEMENT] `sparsezeros(::AbstractNamedUnitRange...)::AbstractNamedDimsArray` Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 20/100

ITensor/SparseArraysBase.jl#79 · Opened Dec 22, 2025
[ITensors] [ENHANCEMENT] Fermionic sign operator for Generic SiteType Open

enhancement ITensors

Difficulty 3/5 1-2 days Newbie friendliness 42/100

ITensor/ITensors.jl#1689 · 1 comment · Opened Dec 16, 2025
[NDTensors] [BUG] Outer fails for two GPU diag tensors Open

bug NDTensors

Difficulty 3/5 1-2 days Newbie friendliness 42/100

ITensor/ITensors.jl#1679 · 6 comments · Opened Nov 11, 2025
[ENHANCEMENT] Use AcceleratedArray (or something similar) as storage of named vertices Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 25/100

ITensor/NamedGraphs.jl#111 · Opened Nov 11, 2025
Problem with TEBD on Fermi-Hubbard model with Electron indices Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ITensor/ITensorMPS.jl#159 · 1 reaction · Opened Oct 6, 2025
[ENHANCEMENT] Overload interface on NamedDimsArrays Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 20/100

ITensor/SparseArraysBase.jl#76 · Opened Sep 5, 2025
[ENHANCEMENT] Have `op_term(::Tuple{Number})` return the identity Open

enhancement

Difficulty 2/5 1-3 hours Newbie friendliness 45/100

ITensor/ITensorMPS.jl#154 · Opened Aug 19, 2025
[ENHANCEMENT] OpSum term to ITensor Open

enhancement

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ITensor/ITensorMPS.jl#150 · 1 comment · Opened Aug 4, 2025
[BUG] write_when_maxdim_exceeds not working for excited state dmrg calculation Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 50/100

ITensor/ITensorMPS.jl#145 · Opened Jun 13, 2025
[ENHANCEMENT] Define `floattype` and `widentype` Open

enhancement

Difficulty 3/5 1-2 days Newbie friendliness 42/100

ITensor/TypeParameterAccessors.jl#53 · Opened Jun 12, 2025
[ENHANCEMENT] Make `in(edge, graph::NamedGraph)` call `has_edge(graph, edge)` Open

enhancement

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

ITensor/NamedGraphs.jl#100 · Opened May 13, 2025
[NDTensors] [BUG] `eigen` for `BlockSparse` incorrectly assumes sorted eigenvalues Open

bug NDTensors

Difficulty 3/5 1-2 days Newbie friendliness 35/100

ITensor/ITensors.jl#1655 · 1 comment · Opened May 8, 2025
[ENHANCEMENT] `Base.map!` needs refactor Open

enhancement

Difficulty 4/5 3-5 days Newbie friendliness 35/100

ITensor/BlockSparseArrays.jl#112 · Opened May 1, 2025
[BUG] Misleading presence of `normalize` keyword in `orthogonalize!` Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 35/100

ITensor/ITensorMPS.jl#140 · 4 comments · Opened Apr 16, 2025
[DISCUSSION] Split off blocked tuples/permutations into separate package Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 20/100

ITensor/TensorAlgebra.jl#49 · Opened Apr 2, 2025
[ENHANCEMENT] Add `eigendecomp` Open

enhancement

Difficulty 5/5 Over a week Newbie friendliness 35/100

ITensor/TensorAlgebra.jl#48 · Opened Apr 1, 2025
[ENHANCEMENT] Run formatter after calling `generate` Open

enhancement

Difficulty 3/5 1-2 days Newbie friendliness 25/100

ITensor/ITensorPkgSkeleton.jl#71 · Opened Mar 27, 2025
[BUG] Fail to add noise to TDVP Open

bug

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ITensor/ITensorMPS.jl#130 · 1 comment · Opened Mar 25, 2025
[NDTensors] [BUG] In-place mul! does not work for BlockSparseTensors Open

bug NDTensors

Difficulty 3/5 1-2 days Newbie friendliness 55/100

ITensor/ITensors.jl#1628 · Opened Mar 13, 2025
[ENHANCEMENT] Consider renaming `eachblockstoredindex` to `blockeachstoredindex` Open

enhancement

ITensor/BlockSparseArrays.jl#72 · 4 comments · 1 assignee · Opened Mar 4, 2025
[ENHANCEMENT] Define `blocksparsezeros`, `blocksparserand`, etc. Open

enhancement

Difficulty 3/5 1-2 days Newbie friendliness 30/100

ITensor/BlockSparseArrays.jl#70 · Opened Mar 3, 2025
[ENHANCEMENT] Store the broadcast style of the blocks in `BlockSparseArrayStyle` Open

enhancement

Difficulty 4/5 3-5 days Newbie friendliness 45/100

ITensor/BlockSparseArrays.jl#60 · Opened Feb 27, 2025
[NDTensors] [ENHANCEMENT] In-Place Versions of basic functions Open

enhancement NDTensors

Difficulty 5/5 Over a week Newbie friendliness 25/100

ITensor/ITensors.jl#1624 · 4 comments · Opened Feb 26, 2025
[ENHANCEMENT] Define `SparseArraysBase.sparse` to convert from dense to sparse, dropping zero values Open

enhancement

Difficulty 3/5 1-2 days Newbie friendliness 45/100

ITensor/SparseArraysBase.jl#34 · 1 comment · Opened Feb 13, 2025

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