Multidimensional arrays with one dimension of length zero #1245
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It's definitely important to allow. The size of a dimension might reflect, for example, the number of apples you have, and you might have zero apples. Functions not handling length-zero dimensions properly is a common source of bugs though. Just have to be careful. |
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On reflection, this does make sense in a mathematical way, it just rubs against my previous more programming-oriented thinking. Thanks! |
jishnub
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) Stdlib: LinearAlgebra URL: https://github.com/JuliaLang/LinearAlgebra.jl.git Stdlib branch: master Julia branch: master Old commit: 1ce8426 New commit: 07725da Julia version: 1.13.0-DEV LinearAlgebra version: 1.12.0(Does not match) Bump invoked by: @jishnub Powered by: [BumpStdlibs.jl](https://github.com/JuliaLang/BumpStdlibs.jl) Diff: JuliaLang/LinearAlgebra.jl@1ce8426...07725da ``` $ git log --oneline 1ce8426..07725da 07725da Branch on `Bool` `alpha` in scaling `mul!` (#1286) 61e444d Fix exponentiation with immutable matrix (#1289) 77475c1 Fix `lmul!`/`rmul!` for 0-sized matrices (#1290) c3d35c0 Test for `versioninfo` with `ENV` variable (#1279) 830ea2f Fit broken matmul test (#1288) 222f7f2 Propagate inbounds in diagzero (#1285) e65e75c Clean up `herk_wrapper!` and add 5-arg tests (#1254) ece1962 `versioninfo`: simplify, improve type stability (#1274) 3e525a8 Speicalize `copy!` for triangular, and use `copy!` in `ldiv` (#1263) 763f19f Forward scaling `lmul!`/`rmul!` for `Tridiagonal` to bands (#1284) 2d27d1c Explicit loop in converting `Bidiagonal`/`Tridiagonal` to `Matrix` (#1283) 0671a7b Simplify small Bidiagonal-AbstractVecOrMat multiplication (#1278) a8fd121 Test for empty `Symmetric` and `BlasFlag.NONE` (#1280) 6e2de14 Remove bounds-checking in `Bidiagonal` `rdiv!` (#1281) 4a8fc62 Test for 5-arg `mul!` c437beb Test for empty `Symmetric` and `BlasFlag.NONE` 7a891e9 Test for `versioninfo` with `ENV` variable 84fd21b Test for `versioninfo` (#1276) 243efdb `AbstractQ` bugfix: define `Base.IteratorSize` (#1277) 6073f28 Ease inference in `Bidiagonal` divmul tests (#1273) 30cb5d6 Avoid copy in empty bidiag `ldiv!` (#1275) 5d3ef46 Skip symmetry check in converting Symmetric to SymTridiagonal (#1269) ae5385b Specialize `isreal` for banded matrices (#1271) 0a253be Explicit loop in `_iszero` for strided views (#1264) 3f46f5f `istril`/`istriu` for opposite triangularity (#1265) cd048eb Tests for `mul!` scaling with mismatched axes (#1266) 26db4c8 Restrict tests to `Number` eltypes 8b21ca6 Tests for `mul!` scaling with mismatched axes 9675c38 Fix minimum band for `UpperTriangular`/`Lowertriangular` aeeed7d Add unit triangular tests 3e1aaac Add banded tests 7fdfb3b Add tests d866014 istril/istriu for opposite triangularity 925acef Return view in `_diag` for `Bidiagonal` (#1258) b1bcca1 Branch on `Bool` `alpha` in diagonal matmul (#1256) e3e9987 `peakflops`: make `eltype` a static parameter of the method (#1253) 781eb5d `peakflops`: make the element type a static parameter of the method e53b50c use smaller matrix size in `peakflops` on 32-bit (#1255) 0c87d0d use smaller matrix size in `peakflops` on 32-bit 0cbf85f Check approx equality in bunchkaufman docstring (#1251) 5e53d12 Avoid accessing unset indices in symmetric copyto! (#1244) e64a3df fix dispatch to herk (#1247) bfdb742 Destination zeros from eltype in zero-length generic_matvecmul (#1241) 16dedb5 Remove redundant adjoint/transpose methods for Symmetric/Hermitian (#1245) 7f1dfe4 stop assuming that you can mutate data structures in other packages at precompile time (#1252) ``` Co-authored-by: jishnub <[email protected]>
LebedevRI
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May 2, 2025
…iaLang#58180) Stdlib: LinearAlgebra URL: https://github.com/JuliaLang/LinearAlgebra.jl.git Stdlib branch: master Julia branch: master Old commit: 1ce8426 New commit: 07725da Julia version: 1.13.0-DEV LinearAlgebra version: 1.12.0(Does not match) Bump invoked by: @jishnub Powered by: [BumpStdlibs.jl](https://github.com/JuliaLang/BumpStdlibs.jl) Diff: JuliaLang/LinearAlgebra.jl@1ce8426...07725da ``` $ git log --oneline 1ce8426..07725da 07725da Branch on `Bool` `alpha` in scaling `mul!` (JuliaLang#1286) 61e444d Fix exponentiation with immutable matrix (JuliaLang#1289) 77475c1 Fix `lmul!`/`rmul!` for 0-sized matrices (JuliaLang#1290) c3d35c0 Test for `versioninfo` with `ENV` variable (JuliaLang#1279) 830ea2f Fit broken matmul test (JuliaLang#1288) 222f7f2 Propagate inbounds in diagzero (JuliaLang#1285) e65e75c Clean up `herk_wrapper!` and add 5-arg tests (JuliaLang#1254) ece1962 `versioninfo`: simplify, improve type stability (JuliaLang#1274) 3e525a8 Speicalize `copy!` for triangular, and use `copy!` in `ldiv` (JuliaLang#1263) 763f19f Forward scaling `lmul!`/`rmul!` for `Tridiagonal` to bands (JuliaLang#1284) 2d27d1c Explicit loop in converting `Bidiagonal`/`Tridiagonal` to `Matrix` (JuliaLang#1283) 0671a7b Simplify small Bidiagonal-AbstractVecOrMat multiplication (JuliaLang#1278) a8fd121 Test for empty `Symmetric` and `BlasFlag.NONE` (JuliaLang#1280) 6e2de14 Remove bounds-checking in `Bidiagonal` `rdiv!` (JuliaLang#1281) 4a8fc62 Test for 5-arg `mul!` c437beb Test for empty `Symmetric` and `BlasFlag.NONE` 7a891e9 Test for `versioninfo` with `ENV` variable 84fd21b Test for `versioninfo` (JuliaLang#1276) 243efdb `AbstractQ` bugfix: define `Base.IteratorSize` (JuliaLang#1277) 6073f28 Ease inference in `Bidiagonal` divmul tests (JuliaLang#1273) 30cb5d6 Avoid copy in empty bidiag `ldiv!` (JuliaLang#1275) 5d3ef46 Skip symmetry check in converting Symmetric to SymTridiagonal (JuliaLang#1269) ae5385b Specialize `isreal` for banded matrices (JuliaLang#1271) 0a253be Explicit loop in `_iszero` for strided views (JuliaLang#1264) 3f46f5f `istril`/`istriu` for opposite triangularity (JuliaLang#1265) cd048eb Tests for `mul!` scaling with mismatched axes (JuliaLang#1266) 26db4c8 Restrict tests to `Number` eltypes 8b21ca6 Tests for `mul!` scaling with mismatched axes 9675c38 Fix minimum band for `UpperTriangular`/`Lowertriangular` aeeed7d Add unit triangular tests 3e1aaac Add banded tests 7fdfb3b Add tests d866014 istril/istriu for opposite triangularity 925acef Return view in `_diag` for `Bidiagonal` (JuliaLang#1258) b1bcca1 Branch on `Bool` `alpha` in diagonal matmul (JuliaLang#1256) e3e9987 `peakflops`: make `eltype` a static parameter of the method (JuliaLang#1253) 781eb5d `peakflops`: make the element type a static parameter of the method e53b50c use smaller matrix size in `peakflops` on 32-bit (JuliaLang#1255) 0c87d0d use smaller matrix size in `peakflops` on 32-bit 0cbf85f Check approx equality in bunchkaufman docstring (JuliaLang#1251) 5e53d12 Avoid accessing unset indices in symmetric copyto! (JuliaLang#1244) e64a3df fix dispatch to herk (JuliaLang#1247) bfdb742 Destination zeros from eltype in zero-length generic_matvecmul (JuliaLang#1241) 16dedb5 Remove redundant adjoint/transpose methods for Symmetric/Hermitian (JuliaLang#1245) 7f1dfe4 stop assuming that you can mutate data structures in other packages at precompile time (JuliaLang#1252) ``` Co-authored-by: jishnub <[email protected]>
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I searched but couldn't find an issue on this, my apologies if I missed it.
I'm somewhat surprised that I can do the following:
Why would it ever be useful to have a dimension of length zero? If it is never useful, why is it allowed?
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