Add left division operator #82
Conversation
Codecov Report
@@ Coverage Diff @@
## master #82 +/- ##
==========================================
+ Coverage 95.65% 95.85% +0.20%
==========================================
Files 5 5
Lines 322 314 -8
==========================================
- Hits 308 301 -7
+ Misses 14 13 -1
Continue to review full report at Codecov.
|
|
@dkarrasch in #39 (comment) what did you mean by checking that the blocks are diagonal? |
Co-authored-by: Miha Zgubic <mzgubic@users.noreply.github.com>
Co-authored-by: Miha Zgubic <mzgubic@users.noreply.github.com>
|
Hmm, what's up with CI? |
|
The new test I added, has issues visibly 😅 |
|
Oh that's because I am using |
| result = similar(vm) | ||
| for block in blocks(B) | ||
| nrow = size(block, 1) | ||
| result[row_i:(row_i + nrow - 1), :] = block \ vm[row_i:(row_i + nrow - 1), :] |
There was a problem hiding this comment.
i've not thought too much, but perhaps you know: is there any rewriting of this that would allow us to access vm col-wise rather than row-wise?
also does using views of vm help performance here at all?
There was a problem hiding this comment.
I don't think accessing vm colwise is possible for this problem.
views could help I suppose. I am going to run some benchmark and see
There was a problem hiding this comment.
Views does not seem to help that much in this simple example
julia> using BenchmarkTools
julia> N = 400
julia> A = BlockDiagonal([rand(N, N) for _ in 1:5])
julia> x = rand(5N, 100)
julia> A \ x
julia> @btime $A \ $x # No views
7.085 ms (37 allocations: 10.70 MiB)
julia> @btime $A \ $x # With views
7.403 ms (27 allocations: 9.17 MiB)There was a problem hiding this comment.
i think the reduced allocations suggests let's use views:
e.g. on a matrix of the same size, but more blocks:
julia> M = 40
julia> B = BlockDiagonal([rand(M, M) for _ in 1:5])
julia> x = rand(5N, 100)
julia> @btime $A \ $x # No views
2.155 ms (302 allocations: 5.22 MiB)
julia> @btime $A \ $x # With views
2.264 ms (202 allocations: 3.69 MiB)(i know the times are ~equal but i usually trust allocations as at least as good a guide in practice)
This follows from the discussion from #39. This is the same implementation presented in the issue.
It is currently done with in place allocation, but I could also change it if you think it would be better.